nvme: remove the NVME_NS_DEAD check in nvme_validate_ns

At the point where namespaces are marked dead, the controller is in a
non-live state and we won't get pass the identify commands.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20221101150050.3510-6-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>