block: Use bdev_open_by_dev() in disk_scan_partitions() and blkdev_bszset()

Convert disk_scan_partitions() and blkdev_bszset() to use
bdev_open_by_dev().

Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-3-jack@suse.cz


Signed-off-by: Christian Brauner <brauner@kernel.org>