block: pass a phys_addr_t to get_max_segment_size

Work on a single address to simplify the logic, and prepare the callers
from using better helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20240706075228.2350978-3-hch@lst.de


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