batman-adv: Convert batadv_neigh_node to kref

batman-adv uses a self-written reference implementation which is just based
on atomic_t. This is less obvious when reading the code than kref and
therefore increases the change that the reference counting will be missed.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 6193c01..68ca39e 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -384,7 +384,7 @@
 	spinlock_t ifinfo_lock;	/* protects ifinfo_list and its members */
 	struct batadv_hard_iface *if_incoming;
 	unsigned long last_seen;
-	atomic_t refcount;
+	struct kref refcount;
 	struct rcu_head rcu;
 };