[NETFILTER]: Remove tasklist_lock abuse in ipt{,6}owner

Rip out cmd/sid/pid matching since its unfixable broken and stands in the
way of locking changes to tasklist_lock.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>