Fix switching extruder

`DONT_SWITCH` got lost along the way. Replace it with `DO_SWITCH_EXTRUDER` and adjust the code.

Marlin/src/module/configuration_store.cpp

@@ -2126,7 +2126,7 @@ void MarlinSettings::reset(PORTARG_SOLO) {
         SERIAL_ECHOPAIR_P(port, "  M218 T", (int)e);
         SERIAL_ECHOPAIR_P(port, " X", LINEAR_UNIT(hotend_offset[X_AXIS][e]));
         SERIAL_ECHOPAIR_P(port, " Y", LINEAR_UNIT(hotend_offset[Y_AXIS][e]));
-        #if ENABLED(DUAL_X_CARRIAGE) || ENABLED(SWITCHING_NOZZLE) ||ENABLED(PARKING_EXTRUDER)
+        #if ENABLED(DUAL_X_CARRIAGE) || ENABLED(SWITCHING_NOZZLE) || ENABLED(PARKING_EXTRUDER)
           SERIAL_ECHOPAIR_P(port, " Z", LINEAR_UNIT(hotend_offset[Z_AXIS][e]));
         #endif
         SERIAL_EOL_P(port);

Marlin/src/module/tool_change.cpp

@@ -57,7 +57,7 @@
   #include "../feature/fanmux.h"
 #endif
 
-#if ENABLED(SWITCHING_EXTRUDER)
+#if DO_SWITCH_EXTRUDER
 
   #if EXTRUDERS > 3
     #define REQ_ANGLES 4
@@ -347,8 +347,6 @@ inline void invalid_extruder_error(const uint8_t e) {
 
 #endif // DUAL_X_CARRIAGE
 
-#define DO_SWITCH_EXTRUDER (SWITCHING_EXTRUDER_SERVO_NR != SWITCHING_NOZZLE_SERVO_NR)
-
 /**
  * Perform a tool-change, which may result in moving the
  * previous tool out of the way and the new tool into place.

Marlin/src/module/tool_change.h

@@ -25,7 +25,7 @@
 
 #include "../inc/MarlinConfig.h"
 
-#if ENABLED(SWITCHING_EXTRUDER)
+#if DO_SWITCH_EXTRUDER
   void move_extruder_servo(const uint8_t e);
 #endif