Merge pull request #5560 from thinkyhead/rc_bl_status

Have bed leveling status output current status, not requested.

Marlin/Marlin_main.cpp

       if (code_seen('Z')) set_z_fade_height(code_value_linear_units());
     #endif
 
-    if (to_enable && !(
+    const bool new_status =
       #if ENABLED(MESH_BED_LEVELING)
         mbl.active()
       #else
         planner.abl_enabled
       #endif
-    ) ) {
-      to_enable = false;
+    ;
+
+    if (to_enable && !new_status) {
       SERIAL_ERROR_START;
       SERIAL_ERRORLNPGM(MSG_ERR_M420_FAILED);
     }
 
     SERIAL_ECHO_START;
-    SERIAL_ECHOLNPAIR("Bed Leveling ", to_enable ? MSG_ON : MSG_OFF);
+    SERIAL_ECHOLNPAIR("Bed Leveling ", new_status ? MSG_ON : MSG_OFF);
 
     // V to print the matrix or mesh
     if (code_seen('V')) {

Marlin/configuration_store.cpp

 
   bool eeprom_write_error;
 
-  void _EEPROM_writeData(int &pos, uint8_t* value, uint16_t size) {
+  void _EEPROM_writeData(int &pos, const uint8_t* value, uint16_t size) {
     if (eeprom_write_error) return;
     while (size--) {
       uint8_t * const p = (uint8_t * const)pos;