Fix #275 Backlight does not get back to MAX brightness after exiting backlight menu entries

Backlight is set to FULL when interacting with backlight menu entries,
but it is not set back to MAX when exiting from those entries. This
commit corrects that behaviour.

ui/menu.c

@@ -488,6 +488,12 @@ void UI_DisplayMenu(void)
 
 	bool already_printed = false;
 
+	/* Brightness is set to max in some entries of this menu. Return it to the configured brightness
+	   level the "next" time we enter here.I.e., when we move from one menu to another.
+	   It also has to be set back to max when pressing the Exit key. */
+
+	BACKLIGHT_SetBrightness(gEeprom.BACKLIGHT_MAX);
+
 	switch (UI_MENU_GetCurrentMenuId())
 	{
 		case MENU_SQL: