ovs: Remove rtnl_lock() from ovs_exit_net()

Here we iterate for_each_net() and removes
vport from alive net to the exiting net.

ovs_net::dps are protected by ovs_mutex(),
and the others, who change it (ovs_dp_cmd_new(),
__dp_destroy()) also take it.
The same with datapath::ports list.

So, we remove rtnl_lock() here.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/openvswitch/datapath.c

@@ -2363,12 +2363,10 @@ static void __net_exit ovs_exit_net(struct net *dnet)
 	list_for_each_entry_safe(dp, dp_next, &ovs_net->dps, list_node)
 		__dp_destroy(dp);
 
-	rtnl_lock();
 	down_read(&net_rwsem);
 	for_each_net(net)
 		list_vports_from_net(net, dnet, &head);
 	up_read(&net_rwsem);
-	rtnl_unlock();
 
 	/* Detach all vports from given namespace. */
 	list_for_each_entry_safe(vport, vport_next, &head, detach_list) {