Remove Contrast Menu for U8GLIB_ST7920

The other two devices we use in u8glib have more than only dummy code.
Checked this in the library code.

Marlin/Conditionals.h

@@ -130,7 +130,6 @@
      #define NEWPANEL
   #endif
 
-
   #ifdef ULTIPANEL
     #define NEWPANEL  //enable this if you have a click-encoder panel
     #define SDSUPPORT
@@ -161,6 +160,13 @@
     #define DEFAULT_LCD_CONTRAST 32
   #endif
 
+  #ifdef DOGLCD
+    #define HAS_LCD_CONTRAST
+    #ifdef U8GLIB_ST7920
+      #undefine HAS_LCD_CONTRAST
+    #endif
+  #endif
+
 #else // CONFIGURATION_LCD
 
   #define CONDITIONALS_H

Marlin/ultralcd.cpp

@@ -58,7 +58,7 @@ static void lcd_status_screen();
   static void lcd_control_temperature_preheat_abs_settings_menu();
   static void lcd_control_motion_menu();
   static void lcd_control_volumetric_menu();
-  #ifdef DOGLCD
+  #ifdef HAS_LCD_CONTRAST
     static void lcd_set_contrast();
   #endif
   #ifdef FWRETRACT
@@ -739,7 +739,7 @@ static void lcd_control_menu() {
   MENU_ITEM(submenu, MSG_MOTION, lcd_control_motion_menu);
   MENU_ITEM(submenu, MSG_VOLUMETRIC, lcd_control_volumetric_menu);
 
-  #ifdef DOGLCD
+  #ifdef HAS_LCD_CONTRAST
     //MENU_ITEM_EDIT(int3, MSG_CONTRAST, &lcd_contrast, 0, 63);
     MENU_ITEM(submenu, MSG_CONTRAST, lcd_set_contrast);
   #endif
@@ -963,8 +963,7 @@ static void lcd_control_volumetric_menu() {
   END_MENU();
 }
 
-#ifdef DOGLCD
-
+#ifdef HAS_LCD_CONTRAST
   static void lcd_set_contrast() {
     if (encoderPosition != 0) {
       lcd_contrast -= encoderPosition;
@@ -976,11 +975,9 @@ static void lcd_control_volumetric_menu() {
     if (lcdDrawUpdate) lcd_implementation_drawedit(PSTR(MSG_CONTRAST), itostr2(lcd_contrast));
     if (LCD_CLICKED) lcd_goto_menu(lcd_control_menu);
   }
-
-#endif // DOGLCD
+#endif // HAS_LCD_CONTRAST
 
 #ifdef FWRETRACT
-
   static void lcd_control_retract_menu() {
     START_MENU();
     MENU_ITEM(back, MSG_CONTROL, lcd_control_menu);
@@ -998,16 +995,13 @@ static void lcd_control_volumetric_menu() {
     MENU_ITEM_EDIT(float3, MSG_CONTROL_RETRACT_RECOVERF, &retract_recover_feedrate, 1, 999);
     END_MENU();
   }
-
 #endif // FWRETRACT
 
 #if SDCARDDETECT == -1
-
   static void lcd_sd_refresh() {
     card.initsd();
     currentMenuViewOffset = 0;
   }
-
 #endif
 
 static void lcd_sd_updir() {
@@ -1458,7 +1452,7 @@ void lcd_setalertstatuspgm(const char* message) {
 
 void lcd_reset_alert_level() { lcd_status_message_level = 0; }
 
-#ifdef DOGLCD
+#ifdef HAS_LCD_CONTRAST
   void lcd_setcontrast(uint8_t value) {
     lcd_contrast = value & 0x3F;
     u8g.setContrast(lcd_contrast);