scsi: xen-scsifront: 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/20210809230355.8186-50-bvanassche@acm.orgSigned-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/xen-scsifront.c

@@ -212,7 +212,7 @@ static int scsifront_do_request(struct vscsifrnt_info *info,
 	memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);
 
 	ring_req->sc_data_direction   = (uint8_t)sc->sc_data_direction;
-	ring_req->timeout_per_command = sc->request->timeout / HZ;
+	ring_req->timeout_per_command = scsi_cmd_to_rq(sc)->timeout / HZ;
 
 	for (i = 0; i < (shadow->nr_segments & ~VSCSIIF_SG_GRANT); i++)
 		ring_req->seg[i] = shadow->seg[i];