These pernet_operations unregister net::ipv4::nat_table table.
Another net/pernet_operations do not send ipv4 packets to foreign
net namespaces. So, we mark them async.
Signed-off-by: NKirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>