Move M301 to cpp

Marlin/src/Marlin.cpp

   return false;
 }
 
-#if ENABLED(PIDTEMP)
-  #include "gcode/config/M301.h"
-#endif
-
 #if ENABLED(PIDTEMPBED)
   #include "gcode/config/M304.h"
 #endif

Marlin/src/gcode/config/M301.h → Marlin/src/gcode/config/M301.cpp

  *
  */
 
+#include "../../inc/MarlinConfig.h"
+
+#if ENABLED(PIDTEMP)
+
+#include "../gcode.h"
+#include "../../module/temperature.h"
+
 /**
  * M301: Set PID parameters P I D (and optionally C, L)
  *
  *   C[float] Kc term
  *   L[float] LPQ length
  */
-void gcode_M301() {
+void GcodeSuite::M301() {
 
   // multi-extruder PID patch: M301 updates or prints a single extruder's PID values
   // default behaviour (omitting E parameter) is to update for extruder 0 only
     SERIAL_ERRORLN(MSG_INVALID_EXTRUDER);
   }
 }
+
+#endif // PIDTEMP

Marlin/src/gcode/gcode.cpp

 extern void gcode_M165();
 extern void gcode_M240();
 extern void gcode_M250();
-extern void gcode_M301();
 extern void gcode_M302();
 extern void gcode_M304();
 extern void gcode_M350();
       #endif
 
       #if ENABLED(PIDTEMP)
-        case 301: // M301: Set hotend PID parameters
-          gcode_M301();
-          break;
-      #endif // PIDTEMP
+        case 301: M301(); break;  // M301: Set hotend PID parameters
+      #endif
 
       #if ENABLED(PIDTEMPBED)
         case 304: // M304: Set bed PID parameters