virtio-blk: remove a spurious call to revalidate_disk_size

revalidate_disk_size just updates the block device size from the disk
size.  Thus calling it from virtblk_update_cache_mode doesn't actually
do anything.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

drivers/block/virtio_blk.c

@@ -598,7 +598,6 @@ static void virtblk_update_cache_mode(struct virtio_device *vdev)
 	struct virtio_blk *vblk = vdev->priv;
 
 	blk_queue_write_cache(vblk->disk->queue, writeback, false);
-	revalidate_disk_size(vblk->disk, true);
 }
 
 static const char *const virtblk_cache_types[] = {