Fix sensorless_homing_per_axis compile warning

Marlin/src/module/motion.cpp

    */
   void sensorless_homing_per_axis(const AxisEnum axis, const bool enable/*=true*/) {
     switch (axis) {
+      default: break;
       #if X_SENSORLESS
         case X_AXIS:
           tmc_sensorless_homing(stepperX, enable);