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: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index e4f27a8..c673b58 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -149,6 +149,8 @@
 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);
 }