dm: fold clone_bio into __clone_and_map_data_bio

Fold clone_bio into its only caller to prepare for refactoring.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20220202160109.108149-4-hch@lst.de


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