brd: pass a bvec pointer to brd_do_bvec

Pass the bvec to brd_do_bvec instead of marshalling the information into
individual arguments.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250428141014.2360063-2-hch@lst.de


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