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: Christoph Hellwig <[e-mail]>
Acked-by: Stefan Hajnoczi <[e-mail]>
Acked-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/block/virtio_blk.c

···
 	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[] = {