block: no need to initialize rq->cmd with blk_get_request

blk_get_request initializes rq->cmd (rq_init does) so the users don't
need to do that.

The purpose of this patch is to remove sizeof(rq->cmd) and &rq->cmd,
as a preparation for large command support, which changes rq->cmd from
the static array to a pointer. sizeof(rq->cmd) will not make sense and
&rq->cmd won't work.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

drivers/md/dm-emc.c

@@ -110,8 +110,6 @@ static struct request *get_failover_req(struct emc_handler *h,
 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 	rq->sense_len = 0;
 
-	memset(&rq->cmd, 0, BLK_MAX_CDB);
-
 	rq->timeout = EMC_FAILOVER_TIMEOUT;
 	rq->cmd_type = REQ_TYPE_BLOCK_PC;
 	rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;

drivers/md/dm-mpath-hp-sw.c

@@ -137,7 +137,6 @@ static struct request *hp_sw_get_request(struct dm_path *path)
 	req->sense = h->sense;
 	memset(req->sense, 0, SCSI_SENSE_BUFFERSIZE);
 
-	memset(&req->cmd, 0, BLK_MAX_CDB);
 	req->cmd[0] = START_STOP;
 	req->cmd[4] = 1;
 	req->cmd_len = COMMAND_SIZE(req->cmd[0]);

drivers/md/dm-mpath-rdac.c

@@ -284,7 +284,6 @@ static struct request *get_rdac_req(struct rdac_handler *h,
 		return NULL;
 	}
 
- 	memset(&rq->cmd, 0, BLK_MAX_CDB);
 	rq->sense = h->sense;
 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 	rq->sense_len = 0;