nvme: bring back auto-removal of deleted namespaces during sequential scan

Bring back the check of the Identify Namespace return value for the
legacy NVMe 1.0-style sequential scanning.  While NVMe 1.0 does not
support namespace management, there are "modern" cloud solutions like
Google Cloud Platform that claim the obsolete 1.0 compliance for no
good reason while supporting proprietary sideband namespace management.

Fixes: 1a893c2b

 ("nvme: refactor namespace probing")
Reported-by: Nils Hanke <nh@edgeless.systems>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Tested-by: Nils Hanke <nh@edgeless.systems>