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>

drivers/nvme/target/admin-cmd.c

@@ -509,7 +509,7 @@ int nvmet_parse_admin_cmd(struct nvmet_req *req)
 		break;
 	case nvme_admin_identify:
 		req->data_len = 4096;
-		switch (le32_to_cpu(cmd->identify.cns)) {
+		switch (cmd->identify.cns) {
 		case NVME_ID_CNS_NS:
 			req->execute = nvmet_execute_identify_ns;
 			return 0;