nvme-pci: fix queue unquiesce check on slot_reset

A zero return means the reset was successfully scheduled. We don't want
to unquiesce the queues while the reset_work is pending, as that will
just flush out requeued requests to a failed completion.

Fixes: 71a5bb15 ("nvme: ensure disabling pairs with unquiesce")
Reported-by: Dhankaran Singh Ajravat <dhankaran@meta.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>