floppy: address add_disk() error handling on probe

We need to cleanup resources on the probe() callback registered
with __register_blkdev(), now that add_disk() error handling is
supported. Address this.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20211103230437.1639990-14-mcgrof@kernel.org


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