scsi: virtio_scsi: Use HCTX_TYPE_DEFAULT for blk_mq_tag_set->map

Use HCTX_TYPE_DEFAULT instead of 0 to avoid hardcoding.
Signed-off-by: NDongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/virtio_scsi.c

@@ -659,7 +659,7 @@ static int virtscsi_abort(struct scsi_cmnd *sc)
 static int virtscsi_map_queues(struct Scsi_Host *shost)
 {
 	struct virtio_scsi *vscsi = shost_priv(shost);
-	struct blk_mq_queue_map *qmap = &shost->tag_set.map[0];
+	struct blk_mq_queue_map *qmap = &shost->tag_set.map[HCTX_TYPE_DEFAULT];
 
 	return blk_mq_virtio_map_queues(qmap, vscsi->vdev, 2);
 }