batman-adv: fix global TT entry deletion

During the last merge involving translation-table.c something went wrong and two
lines disappeared from translation-table.c. This patch recovers them.
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/batman-adv/translation-table.c

@@ -149,6 +149,8 @@ static void batadv_tt_orig_list_entry_free_rcu(struct rcu_head *rcu)
 static void
 batadv_tt_orig_list_entry_free_ref(struct tt_orig_list_entry *orig_entry)
 {
+	/* to avoid race conditions, immediately decrease the tt counter */
+	atomic_dec(&orig_entry->orig_node->tt_size);
 	call_rcu(&orig_entry->rcu, batadv_tt_orig_list_entry_free_rcu);
 }