net: Convert nfnl_queue_net_ops

These pernet_operations register and unregister net::nf::queue_handler
and /proc entry. The handler is accessed only under RCU, so this looks
safe to convert them.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>