Followup to position refactor

Marlin/src/module/tool_change.cpp

       #elif ENABLED(SWITCHING_NOZZLE) && !SWITCHING_NOZZLE_TWO_SERVOS   // Switching Nozzle (single servo)
         // Raise by a configured distance to avoid workpiece, except with
         // SWITCHING_NOZZLE_TWO_SERVOS, as both nozzles will lift instead.
-        current_position.z += _MAX(-zdiff, 0.0) + toolchange_settings.z_raise;
+        current_position.z += _MAX(-diff.z, 0.0) + toolchange_settings.z_raise;
         #if HAS_SOFTWARE_ENDSTOPS
           NOMORE(current_position.z, soft_endstop.max.z);
         #endif