Merge pull request #8048 from madmo/mks-mini-gt2560

[1.1.x] Add MKS MINI 12864 support to GT2560

Marlin/example_configurations/Geeetech/GT2560/Configuration.h

 /**
  * Customize common displays for GT2560
  */
-#if ENABLED(ULTIMAKERCONTROLLER) || ENABLED(REPRAP_DISCOUNT_SMART_CONTROLLER) || ENABLED(G3D_PANEL)
+#if ENABLED(ULTIMAKERCONTROLLER) || ENABLED(REPRAP_DISCOUNT_SMART_CONTROLLER) || ENABLED(G3D_PANEL) || ENABLED(MKS_MINI_12864)
   #define SDSUPPORT   // Force SD Card support on for these displays
 #elif ENABLED(ULTRA_LCD) && ENABLED(DOGLCD) // No panel, just graphical LCD?
   #define LCD_WIDTH 20 // Default is 22. For this Geeetech use 20

Marlin/pins_GT2560_REV_A.h

 
   #if ENABLED(NEWPANEL)
 
-    #define LCD_PINS_RS    20
-    #define LCD_PINS_ENABLE 17
-    #define LCD_PINS_D4    16
-    #define LCD_PINS_D5    21
-    #define LCD_PINS_D6     5
-    #define LCD_PINS_D7     6
+    #if ENABLED(MKS_MINI_12864)
+      #define DOGLCD_A0     5
+      #define DOGLCD_CS    21
+      #define BTN_EN1      40
+      #define BTN_EN2      42
+    #else
+      #define LCD_PINS_RS  20
+      #define LCD_PINS_ENABLE 17
+      #define LCD_PINS_D4  16
+      #define LCD_PINS_D5  21
+      #define LCD_PINS_D6   5
+      #define LCD_PINS_D7   6
+      #define BTN_EN1      42
+      #define BTN_EN2      40
+    #endif
 
-    // Buttons are directly attached
-    #define BTN_EN1        42
-    #define BTN_EN2        40
     #define BTN_ENC        19
-
     #define SD_DETECT_PIN  38
 
   #else // !NEWPANEL