Added MKS MINI 12864 support to FYSETC F6 V1.3 (#12656)

Marlin/src/pins/pins_FYSETC_F6_13.h

   #define BTN_EN1          31
   #define BTN_EN2          33
   #define BTN_ENC          35
+
+  #if ENABLED(MKS_MINI_12864)
+    #define DOGLCD_A0      27
+    #define DOGLCD_CS      25
+  #endif
 #endif