Make dual_x_carriage_mode an enumeration

Marlin/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/Marlin_main.cpp

 
 #if ENABLED(DUAL_X_CARRIAGE)
 
-  #define DXC_FULL_CONTROL_MODE 0
-  #define DXC_AUTO_PARK_MODE    1
-  #define DXC_DUPLICATION_MODE  2
-
-  static int dual_x_carriage_mode = DEFAULT_DUAL_X_CARRIAGE_MODE;
+  static DualXMode dual_x_carriage_mode = DEFAULT_DUAL_X_CARRIAGE_MODE;
 
   static float x_home_pos(int extruder) {
     if (extruder == 0)
    */
   inline void gcode_M605() {
     stepper.synchronize();
-    if (code_seen('S')) dual_x_carriage_mode = code_value_byte();
+    if (code_seen('S')) dual_x_carriage_mode = (DualXMode)code_value_byte();
     switch (dual_x_carriage_mode) {
       case DXC_DUPLICATION_MODE:
         if (code_seen('X')) duplicate_extruder_x_offset = max(code_value_axis_units(X_AXIS), X2_MIN_POS - x_home_pos(0));

Marlin/enum.h

   LCDVIEW_CALL_NO_REDRAW
 };
 
+#if ENABLED(DUAL_X_CARRIAGE)
+  enum DualXMode {
+    DXC_FULL_CONTROL_MODE,
+    DXC_AUTO_PARK_MODE,
+    DXC_DUPLICATION_MODE
+  };
+#endif
+
 #endif // __ENUM_H__

Marlin/example_configurations/Cartesio/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/Felix/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/Hephestos/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/Hephestos_2/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/K8200/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/K8400/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/RigidBot/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/SCARA/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/TAZ4/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/WITBOX/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/delta/biv2.5/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/delta/generic/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/delta/kossel_mini/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/delta/kossel_pro/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/delta/kossel_xl/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/makibox/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder

Marlin/example_configurations/tvrrug/Round2/Configuration_adv.h

   //                           once. (2nd extruder x offset and temp offset are set using: M605 S2 [Xnnn] [Rmmm])
 
   // This is the default power-up mode which can be later using M605.
-  #define DEFAULT_DUAL_X_CARRIAGE_MODE 0
+  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE
 
   // Default settings in "Auto-park Mode"
   #define TOOLCHANGE_PARK_ZLIFT   0.2      // the distance to raise Z axis when parking an extruder