Merge pull request #6039 from Bob-the-Kuhn/M114-sync-with-stepper

M114 - wait for move completion before reporting position

Marlin/Marlin_main.cpp

 /**
  * M114: Output current position to serial port
  */
-inline void gcode_M114() { report_current_position(); }
+inline void gcode_M114() { stepper.synchronize(); report_current_position(); }
 
 /**
  * M115: Capabilities string