eturn NULL pointers.

A more ugly problem that could be caused is packets in flight why the
subsystem is shutting down.

To remove confusion also remove the cruft cause by inappropriately
trying to fix this bug.

With the aid of the previous patch I have tested this patch and
confirmed that using register_pernet_subsys makes the failure go away as
it should.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
üVŸã”@x