scsi: qla2xxx: Declare qla_tgt_cmd.cdb const

Make it clear that the CDB is not modified after processing of a SCSI
command has started.

Cc: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Himanshu Madhani <hmadhani@marvell.com>
Reviewed-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_target.h

@@ -912,7 +912,7 @@ struct qla_tgt_cmd {
 	uint8_t scsi_status, sense_key, asc, ascq;
 
 	struct crc_context *ctx;
-	uint8_t		*cdb;
+	const uint8_t	*cdb;
 	uint64_t	lba;
 	uint16_t	a_guard, e_guard, a_app_tag, e_app_tag;
 	uint32_t	a_ref_tag, e_ref_tag;