[NETFILTER]: nfnetlink_queue: fix checks in nfqnl_recv_config

The peer_pid must be checked in all cases when a queue exists, currently
it is not checked if for NFQA_CFG_QUEUE_MAXLEN when a NFQA_CFG_CMD
attribute exists in some cases. Same for the queue existance check,
which can cause a NULL pointer dereference.

Also consistently return -ENODEV for "queue not found". -ENOENT would
be better, but that is already used to indicate a queued skb id doesn't
exist.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>