net,rcu: convert call_rcu(phonet_device_rcu_free) to kfree_rcu()

The rcu callback phonet_device_rcu_free() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(phonet_device_rcu_free).
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

net/phonet/pn_dev.c

@@ -162,14 +162,6 @@ int phonet_address_add(struct net_device *dev, u8 addr)
 	return err;
 }
 
-static void phonet_device_rcu_free(struct rcu_head *head)
-{
-	struct phonet_device *pnd;
-
-	pnd = container_of(head, struct phonet_device, rcu);
-	kfree(pnd);
-}
-
 int phonet_address_del(struct net_device *dev, u8 addr)
 {
 	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
@@ -188,7 +180,7 @@ int phonet_address_del(struct net_device *dev, u8 addr)
 	mutex_unlock(&pndevs->lock);
 
 	if (pnd)
-		call_rcu(&pnd->rcu, phonet_device_rcu_free);
+		kfree_rcu(pnd, rcu);
 
 	return err;
 }