um: switch to using blk_queue_write_cache()

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

arch/um/drivers/ubd_kern.c

@@ -862,7 +862,7 @@ static int ubd_add(int n, char **error_out)
 		goto out;
 	}
 	ubd_dev->queue->queuedata = ubd_dev;
-	blk_queue_flush(ubd_dev->queue, REQ_FLUSH);
+	blk_queue_write_cache(ubd_dev->queue, true, false);
 
 	blk_queue_max_segments(ubd_dev->queue, MAX_SG);
 	err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);