nvmet: report NPDGL and NPDAL

nvmet: report NPDGL and NPDAL

A block device with a very large discard_granularity queue limit may not
be able to report it in the 16-bit NPDG and NPDA fields in the Identify
Namespace data structure. For this reason, version 2.1 of the NVMe specs
added 32-bit fields NPDGL and NPDAL to the NVM Command Set Specific
Identify Namespace structure. So report the discard_granularity there
too and set OPTPERF to 11b to indicate those fields are supported.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>