phonet: use call_rcu for phonet device free

Use call_rcu rather than synchronize_rcu.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/phonet/pn_dev.h b/include/net/phonet/pn_dev.h
index d7b989c..2d16783 100644
--- a/include/net/phonet/pn_dev.h
+++ b/include/net/phonet/pn_dev.h
@@ -34,6 +34,7 @@
 	struct list_head list;
 	struct net_device *netdev;
 	DECLARE_BITMAP(addrs, 64);
+	struct rcu_head	rcu;
 };
 
 int phonet_device_init(void);