Easier override of ST7920 LCD timing

Marlin/src/pins/pins_ANET_10.h

     #define BTN_EN1          11
     #define BTN_EN2          10
     #define BTN_ENC          16
-    #define ST7920_DELAY_1 DELAY_0_NOP
-    #define ST7920_DELAY_2 DELAY_1_NOP
-    #define ST7920_DELAY_3 DELAY_2_NOP
+    #ifndef ST7920_DELAY_1
+      #define ST7920_DELAY_1 DELAY_0_NOP
+    #endif
+    #ifndef ST7920_DELAY_2
+      #define ST7920_DELAY_2 DELAY_1_NOP
+    #endif
+    #ifndef ST7920_DELAY_3
+      #define ST7920_DELAY_3 DELAY_2_NOP
+    #endif
     #define STD_ENCODER_PULSES_PER_STEP 4
     #define STD_ENCODER_STEPS_PER_MENU_ITEM 1
   #endif

Marlin/src/pins/pins_MELZI_CREALITY.h

 #define FIL_RUNOUT_PIN     -1 // Uses Beeper/LED Pin Pulled to GND
 
 // Alter timing for graphical display
-#define ST7920_DELAY_1 DELAY_2_NOP
-#define ST7920_DELAY_2 DELAY_2_NOP
-#define ST7920_DELAY_3 DELAY_2_NOP
+#ifndef ST7920_DELAY_1
+  #define ST7920_DELAY_1 DELAY_2_NOP
+#endif
+#ifndef ST7920_DELAY_2
+  #define ST7920_DELAY_2 DELAY_2_NOP
+#endif
+#ifndef ST7920_DELAY_3
+  #define ST7920_DELAY_3 DELAY_2_NOP
+#endif
 
 #if ENABLED(MINIPANEL)
   #undef DOGLCD_CS

Marlin/src/pins/pins_MELZI_MALYAN.h

 #define BTN_ENC         28
 
 // Alter timing for graphical display
-#define ST7920_DELAY_1 DELAY_2_NOP
-#define ST7920_DELAY_2 DELAY_2_NOP
-#define ST7920_DELAY_3 DELAY_2_NOP
+#ifndef ST7920_DELAY_1
+  #define ST7920_DELAY_1 DELAY_2_NOP
+#endif
+#ifndef ST7920_DELAY_2
+  #define ST7920_DELAY_2 DELAY_2_NOP
+#endif
+#ifndef ST7920_DELAY_3
+  #define ST7920_DELAY_3 DELAY_2_NOP
+#endif

Marlin/src/pins/pins_MELZI_TRONXY.h

 #define BTN_EN2         11
 #define BTN_ENC         26
 
-#define ST7920_DELAY_1 DELAY_0_NOP
-#define ST7920_DELAY_2 DELAY_2_NOP
-#define ST7920_DELAY_3 DELAY_0_NOP
+#ifndef ST7920_DELAY_1
+  #define ST7920_DELAY_1 DELAY_0_NOP
+#endif
+#ifndef ST7920_DELAY_2
+  #define ST7920_DELAY_2 DELAY_2_NOP
+#endif
+#ifndef ST7920_DELAY_3
+  #define ST7920_DELAY_3 DELAY_0_NOP
+#endif

Marlin/src/pins/pins_PRINTRBOARD_REVF.h

     //#define MISO         23  //        13               B3                ICSP-06             EXP2-05
 
     // increase delays
-    #define ST7920_DELAY_1 DELAY_5_NOP
-    #define ST7920_DELAY_2 DELAY_5_NOP
-    #define ST7920_DELAY_3 DELAY_5_NOP
+    #ifndef ST7920_DELAY_1
+      #define ST7920_DELAY_1 DELAY_5_NOP
+    #endif
+    #ifndef ST7920_DELAY_2
+      #define ST7920_DELAY_2 DELAY_5_NOP
+    #endif
+    #ifndef ST7920_DELAY_3
+      #define ST7920_DELAY_3 DELAY_5_NOP
+    #endif
 
   #else