sd: open code revalidate_disk

Instead of calling revalidate_disk just do the work directly by
calling sd_revalidate_disk, and revalidate_disk_size where needed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>