Fix SPI on SMART RAMPS with mega2560 (#21128)

Marlin/src/lcd/dogm/marlinui_DOGM.h

@@ -88,7 +88,8 @@
 
   #define SMART_RAMPS MB(RAMPS_SMART_EFB, RAMPS_SMART_EEB, RAMPS_SMART_EFF, RAMPS_SMART_EEF, RAMPS_SMART_SF)
   #define U8G_CLASS U8GLIB_64128N_2X_HAL                        // 4 stripes (HW-SPI)
-  #if SMART_RAMPS || DOGLCD_SCK != SD_SCK_PIN || DOGLCD_MOSI != SD_MOSI_PIN
+
+  #if (SMART_RAMPS && defined(__SAM3X8E__)) || DOGLCD_SCK != SD_SCK_PIN || DOGLCD_MOSI != SD_MOSI_PIN
     #define FORCE_SOFT_SPI                                      // SW-SPI
   #endif