scsi: zfcp: 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/20210809230355.8186-11-bvanassche@acm.org
Acked-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-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/s390/scsi/zfcp_fsf.c

@@ -2377,7 +2377,7 @@ static void zfcp_fsf_req_trace(struct zfcp_fsf_req *req, struct scsi_cmnd *scsi)
 		}
 	}
 
-	blk_add_driver_data(scsi->request, &blktrc, sizeof(blktrc));
+	blk_add_driver_data(scsi_cmd_to_rq(scsi), &blktrc, sizeof(blktrc));
 }
 
 /**