Allow Creality V4 SERVO0 and PROBE pin overrides (#21770)

Marlin/src/pins/stm32f1/pins_CREALITY_V4.h

@@ -58,10 +58,12 @@
 //
 // Servos
 //
-#ifndef HAS_PIN_27_BOARD
-  #define SERVO0_PIN                        PB0   // BLTouch OUT
-#else
-  #define SERVO0_PIN                        PC6
+#ifndef SERVO0_PIN
+  #ifndef HAS_PIN_27_BOARD
+    #define SERVO0_PIN                      PB0   // BLTouch OUT
+  #else
+    #define SERVO0_PIN                      PC6
+  #endif
 #endif
 
 //
@@ -71,7 +73,9 @@
 #define Y_STOP_PIN                          PA6
 #define Z_STOP_PIN                          PA7
 
-#define Z_MIN_PROBE_PIN                     PB1   // BLTouch IN
+#ifndef Z_MIN_PROBE_PIN
+  #define Z_MIN_PROBE_PIN                   PB1   // BLTouch IN
+#endif
 
 //
 // Filament Runout Sensor