GT2560 Rev.A Plus Z Max Pin with BLTouch (#21375)

Marlin/src/pins/mega/pins_GT2560_REV_A.h

 #if ENABLED(BLTOUCH)
   #if MB(GT2560_REV_A_PLUS)
     #define SERVO0_PIN                        11
+    #define Z_MAX_PIN                         32
   #else
     #define SERVO0_PIN                        32
+    #define Z_MAX_PIN                         -1
   #endif
-  #define Z_MAX_PIN                           -1
 #else
   #define Z_MAX_PIN                           32
 #endif