More robust HAS_LCD_CONTRAST

Marlin/src/inc/Conditionals_LCD.h

@@ -325,7 +325,7 @@
 /**
  * Default LCD contrast for Graphical LCD displays
  */
-#define HAS_LCD_CONTRAST HAS_GRAPHICAL_LCD && defined(DEFAULT_LCD_CONTRAST)
+#define HAS_LCD_CONTRAST (HAS_GRAPHICAL_LCD && defined(DEFAULT_LCD_CONTRAST))
 #if HAS_LCD_CONTRAST
   #ifndef LCD_CONTRAST_MIN
     #define LCD_CONTRAST_MIN 0