batman-adv: hash_add() has to discriminate on the return value

hash_add() returns 0 on success while returns -1 either on error and on
entry already present. The caller could use such information to select
its behaviour. For this reason it is useful that hash_add() returns -1
in case on error and returns 1 in case of entry already present.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index f3c3f62..d448018 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -252,7 +252,7 @@
 
 	hash_added = hash_add(bat_priv->orig_hash, compare_orig,
 			      choose_orig, orig_node, &orig_node->hash_entry);
-	if (hash_added < 0)
+	if (hash_added != 0)
 		goto free_bcast_own_sum;
 
 	return orig_node;