batman-adv: move neigh_node->if_incoming->if_status check in find_router()

Every time that find_router() is invoked, if_status has to be compared with
IF_ACTIVE. Moving this comparison inside find_router() will avoid to write it
each time.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index bb1c3ec..8c403ce 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -1240,6 +1240,9 @@
 		router = find_ifalter_router(primary_orig_node, recv_if);
 
 return_router:
+	if (router && router->if_incoming->if_status != IF_ACTIVE)
+		goto err_unlock;
+
 	rcu_read_unlock();
 	return router;
 err_unlock: