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/[e-mail]
Acked-by: Benjamin Block <[e-mail]>
Reviewed-by: Hannes Reinecke <[e-mail]>
Signed-off-by: Bart Van Assche <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/s390/scsi/zfcp_fsf.c

···
 		}
 	}
 
-	blk_add_driver_data(scsi->request, &blktrc, sizeof(blktrc));
+	blk_add_driver_data(scsi_cmd_to_rq(scsi), &blktrc, sizeof(blktrc));
 }
 
 /**