nvme: Use CNS as 8-bit field and avoid endianness conversion
This patch defines CNS field as 8-bit field and avoids cpu_to/from_le
conversions.
Also initialize nvme_command cns value explicitly to NVME_ID_CNS_NS
for readability (don't rely on the fact that NVME_ID_CNS_NS = 0).
Reviewed-by: Max Gurtovoy <maxg@mellanox.com> Signed-off-by: Parav Pandit <parav@mellanox.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Jens Axboe <axboe@fb.com>