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

The rcu callback dn_dev_free_ifa_rcu() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(dn_dev_free_ifa_rcu).
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/decnet/dn_dev.c

@@ -332,14 +332,9 @@ static struct dn_ifaddr *dn_dev_alloc_ifa(void)
 	return ifa;
 }
 
-static void dn_dev_free_ifa_rcu(struct rcu_head *head)
-{
-	kfree(container_of(head, struct dn_ifaddr, rcu));
-}
-
 static void dn_dev_free_ifa(struct dn_ifaddr *ifa)
 {
-	call_rcu(&ifa->rcu, dn_dev_free_ifa_rcu);
+	kfree_rcu(ifa, rcu);
 }
 
 static void dn_dev_del_ifa(struct dn_dev *dn_db, struct dn_ifaddr __rcu **ifap, int destroy)