hw/block/nvme: conditionally enable DULBE for zoned namespaces

hw/block/nvme: conditionally enable DULBE for zoned namespaces

The device uses the BDRV_BLOCK_ZERO flag to determine the "deallocated"
status of logical blocks. Since the zoned namespaces command set
specification defines that logical blocks SHALL be marked as deallocated
when the zone is in the Empty or Offline states, DULBE can only be
supported if the zone size is a multiple of the calculated deallocation
granularity (reported in NPDG) which depends on the underlying block
device cluster size (if applicable) or the configured
discard_granularity.

Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>