Revert "blk-cgroup: delay calling blkcg_exit_disk until disk_release"

This reverts commit c43332fe as it is not
needed without moving to disk references in the blkg.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230214183308.1658775-3-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>