Store EEPROM config in flash (#14923)

Avoid confusion between the 2 possible SDs...

Marlin/src/pins/stm32/pins_BIGTREE_SKR_MINI_V1_1.h

 #ifndef ST7920_DELAY_3
   #define ST7920_DELAY_3 DELAY_NS(125)
 #endif
+
+#define FLASH_EEPROM_EMULATION
+#define EEPROM_PAGE_SIZE     (0x800) // 2KB
+#define EEPROM_START_ADDRESS (0x8000000 + (256 * 1024) - 2 * EEPROM_PAGE_SIZE)
+#define E2END                (EEPROM_PAGE_SIZE - 1)