net: don't use INIT_RCU_HEAD

call_rcu() will unconditionally rewrite RCU head anyway.
Applies to 
	struct neigh_parms
	struct neigh_table
	struct net
	struct cipso_v4_doi
	struct in_ifaddr
	struct in_device
	rt->u.dst

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 56fce3a..0bff576 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -112,13 +112,7 @@
 
 static struct in_ifaddr *inet_alloc_ifa(void)
 {
-	struct in_ifaddr *ifa = kzalloc(sizeof(*ifa), GFP_KERNEL);
-
-	if (ifa) {
-		INIT_RCU_HEAD(&ifa->rcu_head);
-	}
-
-	return ifa;
+	return kzalloc(sizeof(struct in_ifaddr), GFP_KERNEL);
 }
 
 static void inet_rcu_free_ifa(struct rcu_head *head)
@@ -161,7 +155,6 @@
 	in_dev = kzalloc(sizeof(*in_dev), GFP_KERNEL);
 	if (!in_dev)
 		goto out;
-	INIT_RCU_HEAD(&in_dev->rcu_head);
 	memcpy(&in_dev->cnf, dev_net(dev)->ipv4.devconf_dflt,
 			sizeof(in_dev->cnf));
 	in_dev->cnf.sysctl = NULL;