ublk: pass 'const struct ublk_io *' to ublk_[un]map_io()

Pass 'const struct ublk_io *' to ublk_[un]map_io() since just io->addr
and io->res are read in the two helpers.

Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250713143415.2857561-11-ming.lei@redhat.com


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