Update ExtUI sanity checks

Marlin/src/inc/SanityCheck.h

       && DISABLED(MKS_12864OLED_SSD1306) ) \
   + (ENABLED(REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER) && DISABLED(BQ_LCD_SMART_CONTROLLER)) \
   + ENABLED(LCD_FOR_MELZI) \
-  + ENABLED(MALYAN_LCD) \
   + ENABLED(MKS_12864OLED) \
   + ENABLED(MKS_12864OLED_SSD1306) \
   + ENABLED(MAKEBOARD_MINI_2_LINE_DISPLAY_1602) \
   + ENABLED(OLED_PANEL_TINYBOY2) \
   + ENABLED(ZONESTAR_LCD) \
   + ENABLED(ULTI_CONTROLLER) \
-  + (ENABLED(EXTENSIBLE_UI) && DISABLED(MALYAN_LCD))
+  + ENABLED(MALYAN_LCD) \
+  + ENABLED(DGUS_LCD) \
+  + (ENABLED(EXTENSIBLE_UI) && DISABLED(MALYAN_LCD, DGUS_LCD))
   #error "Please select no more than one LCD controller option."
 #endif