Fix compiler warnings:

sketch/Marlin.h:178:17: warning: extra tokens at end of #undef directive
sketch/Marlin.h:181:24: warning: extra tokens at end of #undef directive
sketch/Marlin.h:182:0: warning: "enable_z" redefined

Firmware/Marlin.h

@@ -173,14 +173,14 @@ void manage_inactivity(bool ignore_stepper_queue=false);
 #endif
 
 #ifdef PSU_Delta
-void init_force_z();
-void check_force_z();
-#undef disable_z()
-#define disable_z() disable_force_z()
-void disable_force_z();
-#undef enable_disable_z()
-#define enable_z() enable_force_z()
-void enable_force_z();
+    void init_force_z();
+    void check_force_z();
+    #undef disable_z
+    #define disable_z() disable_force_z()
+    void disable_force_z();
+    #undef enable_z
+    #define enable_z() enable_force_z()
+    void enable_force_z();
 #endif // PSU_Delta