block/ataflop: use the blk_cleanup_disk() helper

Use the helper to replace two lines with one.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20210927220302.1073499-12-mcgrof@kernel.org


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