nvme-tcp: fence TCP socket on receive error

Ensure that no further socket reads occur after a receive processing
error, either from io_work being re-scheduled or nvme_tcp_poll.

Failing to do so can result in unrecognised PDU payloads or TCP stream
garbage being processed as a C2H data PDU, and potentially start copying
the payload to an invalid destination after looking up a request using a
bogus command id.

Signed-off-by: Chris Leech <cleech@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: John Meneghini <jmeneghi@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>