cdrom: remove the unused bdev argument to cdrom_open

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Phillip Potter <phil@philpotter.co.uk>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-3-hch@lst.de


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