dm: change max_io_len() to use blk_max_size_offset()

static sector_t max_io_len(sector_t sector, struct dm_target *ti)

{

	sector_t len = max_io_len_target_boundary(sector, ti);

	sector_t offset, max_len;

	sector_t max_len;

	/*

	 * Does the target need to split even further?

	 * - q->limits.chunk_sectors reflects ti->max_io_len so

	 *   blk_max_size_offset() provides required splitting.

	 * - blk_max_size_offset() also respects q->limits.max_sectors

	 */

	if (ti->max_io_len) {

		offset = dm_target_offset(ti, sector);

		if (unlikely(ti->max_io_len & (ti->max_io_len - 1)))

			max_len = sector_div(offset, ti->max_io_len);

		else

			max_len = offset & (ti->max_io_len - 1);

		max_len = ti->max_io_len - max_len;

	max_len = blk_max_size_offset(dm_table_get_md(ti->table)->queue,

				      dm_target_offset(ti, sector));

	if (len > max_len)

		len = max_len;

	}

	return len;

}