batman-adv: unify flags access style in tt global add

This should slightly improve readability
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

net/batman-adv/translation-table.c

@@ -1435,7 +1435,7 @@ static bool batadv_tt_global_add(struct batadv_priv *bat_priv,
 		 * TT_CLIENT_WIFI, therefore they have to be copied in the
 		 * client entry
 		 */
-		tt_global_entry->common.flags |= flags;
+		common->flags |= flags;
 
 		/* If there is the BATADV_TT_CLIENT_ROAM flag set, there is only
 		 * one originator left in the list and we previously received a