Fix MKS MINI12864 on SKR 1.3 (#15836)

Marlin/src/HAL/HAL_LPC1768/u8g/u8g_com_HAL_LPC1768_sw_spi.cpp

 static uint8_t SPI_speed = 0;
 
 static void u8g_sw_spi_HAL_LPC1768_shift_out(uint8_t dataPin, uint8_t clockPin, uint8_t val) {
-  #if ENABLED(FYSETC_MINI_12864)
+  #if EITHER(FYSETC_MINI_12864, MKS_MINI_12864)
     swSpiTransfer_mode_3(val, SPI_speed, clockPin, -1, dataPin);
   #else
     swSpiTransfer_mode_0(val, SPI_speed, clockPin, -1, dataPin);
       break;
 
     case U8G_COM_MSG_CHIP_SELECT:
-      #if ENABLED(FYSETC_MINI_12864)           // LCD SPI is running mode 3 while SD card is running mode 0
-        if (arg_val) {                         //   SCK idle state needs to be set to the proper idle state before
-                                               //   the next chip select goes active
-          u8g_SetPILevel(u8g, U8G_PI_SCK, 1);  // Set SCK to mode 3 idle state before CS goes active
+      #if EITHER(FYSETC_MINI_12864, MKS_MINI_12864)  // LCD SPI is running mode 3 while SD card is running mode 0
+        if (arg_val) {                               //   SCK idle state needs to be set to the proper idle state before
+                                                     //   the next chip select goes active
+          u8g_SetPILevel(u8g, U8G_PI_SCK, 1);        // Set SCK to mode 3 idle state before CS goes active
           u8g_SetPILevel(u8g, U8G_PI_CS, LOW);
         }
         else {

Marlin/src/pins/lpc1768/pins_BIGTREE_SKR_V1.3.h

       #define DOGLCD_A0    P1_19
       #define DOGLCD_SCK   P0_15
       #define DOGLCD_MOSI  P0_18
-      #define FORCE_SOFT_SPI
 
       #define LCD_BACKLIGHT_PIN -1
 
     #else // !FYSETC_MINI_12864
 
       #if ENABLED(MKS_MINI_12864)
-        #define DOGLCD_CS  P1_21
-        #define DOGLCD_A0  P1_22
+        #define DOGLCD_CS    P1_21
+        #define DOGLCD_A0    P1_22
+        #define DOGLCD_SCK   P0_15
+        #define DOGLCD_MOSI  P0_18
+        #define FORCE_SOFT_SPI
       #endif
 
       #if ENABLED(ULTIPANEL)