mtd: bcm47xxpart: simplify size calculation to one loop

	 * Assume that partitions end at the beginning of the one they are

	 * followed by.

	 */

	for (i = 0; i < curr_part - 1; i++)

		parts[i].size = parts[i + 1].offset - parts[i].offset;

	if (curr_part > 0)

		parts[curr_part - 1].size =

				master->size - parts[curr_part - 1].offset;

	for (i = 0; i < curr_part; i++) {

		u64 next_part_offset = (i < curr_part - 1) ?

				       parts[i + 1].offset : master->size;

		parts[i].size = next_part_offset - parts[i].offset;

	}

	*pparts = parts;

	return curr_part;