scsi: 53c700: Use scsi_cmd_to_rq() instead of scsi_cmnd.request

Prepare for removal of the request pointer by using scsi_cmd_to_rq()
instead. This patch does not change any functionality.

Link: https://lore.kernel.org/r/20210809230355.8186-12-bvanassche@acm.orgReviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/53c700.c

@@ -1823,7 +1823,7 @@ NCR_700_queuecommand_lck(struct scsi_cmnd *SCp, void (*done)(struct scsi_cmnd *)
 
 	if ((hostdata->tag_negotiated & (1<<scmd_id(SCp))) &&
 	    SCp->device->simple_tags) {
-		slot->tag = SCp->request->tag;
+		slot->tag = scsi_cmd_to_rq(SCp)->tag;
 		CDEBUG(KERN_DEBUG, SCp, "sending out tag %d, slot %p\n",
 		       slot->tag, slot);
 	} else {