Fix CR10 Stock Display timing with SKR_PRO V1.1 (#15446)

Marlin/src/pins/stm32/pins_BIGTREE_SKR_PRO_V1.1.h

     #define LCD_PINS_ENABLE PG7
     #define LCD_PINS_D4    PG3
 
+    // CR10_Stock Display needs a different delay setting on SKR PRO v1.1, so undef it here. 
+    // It will be defined again at the #HAS_GRAPHICAL_LCD section below.
+    #undef ST7920_DELAY_1
+    #undef ST7920_DELAY_2
+    #undef ST7920_DELAY_3
+
+
   #else
 
     #define LCD_PINS_RS    PD10