block: make bvec_try_merge_hw_page() non-static

This will be used for multi-page configuration for integrity payload.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jinyoung Choi <j-young.choi@samsung.com>
Tested-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20230803024827epcms2p838d9e9131492c86a159fff25d195658f@epcms2p8


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