Use st_get_position_mm where possible (PR#2411)

Marlin/Marlin_main.cpp

         float x_tmp = current_position[X_AXIS] + X_PROBE_OFFSET_FROM_EXTRUDER,
               y_tmp = current_position[Y_AXIS] + Y_PROBE_OFFSET_FROM_EXTRUDER,
               z_tmp = current_position[Z_AXIS],
-              real_z = (float)st_get_position(Z_AXIS) / axis_steps_per_unit[Z_AXIS];  //get the real Z (since the auto bed leveling is already correcting the plane)
+              real_z = st_get_position_mm(Z_AXIS);  //get the real Z (since the auto bed leveling is already correcting the plane)
 
         apply_rotation_xyz(plan_bed_level_matrix, x_tmp, y_tmp, z_tmp); // Apply the correction sending the probe offset
         //line below controls z probe offset, zprobe_zoffset is the actual offset that can be modified via m851 or is read from EEPROM
   SERIAL_PROTOCOL(current_position[E_AXIS]);
 
   SERIAL_PROTOCOLPGM(MSG_COUNT_X);
-  SERIAL_PROTOCOL(float(st_get_position(X_AXIS))/axis_steps_per_unit[X_AXIS]);
+  SERIAL_PROTOCOL(st_get_position_mm(X_AXIS));
   SERIAL_PROTOCOLPGM(" Y:");
-  SERIAL_PROTOCOL(float(st_get_position(Y_AXIS))/axis_steps_per_unit[Y_AXIS]);
+  SERIAL_PROTOCOL(st_get_position_mm(Y_AXIS));
   SERIAL_PROTOCOLPGM(" Z:");
-  SERIAL_PROTOCOL(float(st_get_position(Z_AXIS))/axis_steps_per_unit[Z_AXIS]);
+  SERIAL_PROTOCOL(st_get_position_mm(Z_AXIS));
 
   SERIAL_EOL;
 

Marlin/stepper.cpp

   return count_pos;
 }
 
-#ifdef ENABLE_AUTO_BED_LEVELING
-
-  float st_get_position_mm(AxisEnum axis) {
-    return st_get_position(axis) / axis_steps_per_unit[axis];
-  }
-
-#endif  // ENABLE_AUTO_BED_LEVELING
+float st_get_position_mm(AxisEnum axis) { return st_get_position(axis) / axis_steps_per_unit[axis]; }
 
 void finishAndDisableSteppers() {
   st_synchronize();

Marlin/stepper.h

 // Get current position in steps
 long st_get_position(uint8_t axis);
 
-#ifdef ENABLE_AUTO_BED_LEVELING
-  // Get current position in mm
-  float st_get_position_mm(AxisEnum axis);
-#endif
+// Get current position in mm
+float st_get_position_mm(AxisEnum axis);
 
 // The stepper subsystem goes to sleep when it runs out of things to execute. Call this
 // to notify the subsystem that it is time to go to work.