block: use memcpy_to_bvec in copy_to_high_bio_irq

Use memcpy_to_bvec instead of opencoding the logic.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210727055646.118787-12-hch@lst.de


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