nvme-fc: correct hang in nvme_ns_remove()

nvme-fc: correct hang in nvme_ns_remove()

When connectivity is lost to a device, the association is terminated
and the blk-mq queues are quiesced/stopped. When connectivity is
re-established, they are resumed.

If connectivity is lost for a sufficient amount of time that the
controller is then deleted, the delete path starts tearing down queues,
and eventually calling nvme_ns_remove(). It appears that pending
commands may cause blk_cleanup_queue() to never complete and the
teardown stalls.

Correct by starting the ns queues after transitioning to a DELETING
state, allowing pending commands to be flushed with io failures. Thus
the delete path is clear when reached.

Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>