drm: Shrink mode->type to u8

We only have 7 bits defined for mode->type. Shrink the storage to u8.
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200428171940.19552-7-ville.syrjala@linux.intel.com

include/drm/drm_modes.h

@@ -271,7 +271,7 @@ struct drm_display_mode {
 	 *    which are stuck around for hysterical raisins only. No one has an
 	 *    idea what they were meant for. Don't use.
 	 */
-	unsigned int type;
+	u8 type;
 
 	/**
 	 * @clock: