net: Remove rtnl_lock() in nf_ct_iterate_destroy()

rtnl_lock() doesn't protect net::ct::count,
and it's not needed for__nf_ct_unconfirmed_destroy()
and for nf_queue_nf_hook_drop().
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/nf_conntrack_core.c

@@ -1763,7 +1763,6 @@ nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data), void *data)
 {
 	struct net *net;
 
-	rtnl_lock();
 	down_read(&net_rwsem);
 	for_each_net(net) {
 		if (atomic_read(&net->ct.count) == 0)
@@ -1772,7 +1771,6 @@ nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data), void *data)
 		nf_queue_nf_hook_drop(net);
 	}
 	up_read(&net_rwsem);
-	rtnl_unlock();
 
 	/* Need to wait for netns cleanup worker to finish, if its
 	 * running -- it might have deleted a net namespace from