rcu: convert uses of rcu_assign_pointer(x, NULL) to RCU_INIT_POINTER

When assigning a NULL value to an RCU protected pointer, no barrier
is needed. The rcu_assign_pointer, used to handle that but will soon
change to not handle the special case.

Convert all rcu_assign_pointer of NULL value.

//smpl
@@ expression P; @@

- rcu_assign_pointer(P, NULL)
+ RCU_INIT_POINTER(P, NULL)

// </smpl>

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/netfilter/ebtable_broute.c

@@ -87,14 +87,14 @@ static int __init ebtable_broute_init(void)
 	if (ret < 0)
 		return ret;
 	/* see br_input.c */
-	rcu_assign_pointer(br_should_route_hook,
+	RCU_INIT_POINTER(br_should_route_hook,
 			   (br_should_route_hook_t *)ebt_broute);
 	return 0;
 }
 
 static void __exit ebtable_broute_fini(void)
 {
-	rcu_assign_pointer(br_should_route_hook, NULL);
+	RCU_INIT_POINTER(br_should_route_hook, NULL);
 	synchronize_net();
 	unregister_pernet_subsys(&broute_net_ops);
 }