Correctly calculate backlight level

quantum/visualizer/visualizer.c

@@ -289,7 +289,7 @@ static DECLARE_THREAD_FUNCTION(visualizerThread, arg) {
             if(current_status.backlight_level != state.status.backlight_level) {
                 if (current_status.backlight_level != 0) {
                     gdispGSetPowerMode(LED_DISPLAY, powerOn);
-                    uint16_t percent = (uint16_t)current_status.backlight_level * 100 / 255;
+                    uint16_t percent = (uint16_t)current_status.backlight_level * 100 / BACKLIGHT_LEVELS;
                     gdispGSetBacklight(LED_DISPLAY, percent);
                 }
                 else {