Fix MMU2 compile with include (#21809)

Marlin/src/lcd/menu/menu_mmu2.cpp

@@ -24,6 +24,7 @@
 
 #if BOTH(HAS_LCD_MENU, MMU2_MENUS)
 
+#include "../../MarlinCore.h"
 #include "../../feature/mmu/mmu2.h"
 #include "menu_mmu2.h"
 #include "menu_item.h"