Add M524 to abort SD printing (#12155)

Marlin/src/lcd/ultralcd.h

@@ -288,10 +288,5 @@
   void lcd_reselect_last_file();
 #endif
 
-#if (ENABLED(EXTENSIBLE_UI) || ENABLED(ULTIPANEL)) && ENABLED(SDSUPPORT)
-  extern bool abort_sd_printing;
-#else
-  constexpr bool abort_sd_printing = false;
-#endif
 
 #endif // ULTRALCD_H