block: move clearing bd_invalidated into check_disk_size_change

Both callers of check_disk_size_change clear bd_invalidate directly
after the call, so move the clearing into check_disk_size_change
itself.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>