block: factor out a bd_end_claim helper from blkdev_put

Move all the logic to release an exclusive claim into a helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-2-hch@lst.de


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