mtd: rawnand: brcmnand: improve hamming oob layout

	struct brcmnand_cfg *cfg = &host->hwcfg;

	int sas = cfg->spare_area_size << cfg->sector_size_1k;

	int sectors = cfg->page_size / (512 << cfg->sector_size_1k);

	u32 next;

	if (section >= sectors * 2)

	if (section > sectors)

		return -ERANGE;

	oobregion->offset = (section / 2) * sas;

	next = (section * sas);

	if (section < sectors)

		next += 6;

	if (section & 1) {

		oobregion->offset += 9;

		oobregion->length = 7;

	if (section) {

		oobregion->offset = ((section - 1) * sas) + 9;

	} else {

		oobregion->length = 6;

		/* First sector of each page may have BBI */

		if (!section) {

			/*

			 * Small-page NAND use byte 6 for BBI while large-page

			 * NAND use bytes 0 and 1.

			 */

		if (cfg->page_size > 512) {

				oobregion->offset += 2;

				oobregion->length -= 2;

			/* Large page NAND uses first 2 bytes for BBI */

			oobregion->offset = 2;

		} else {

				oobregion->length--;

			}

			/* Small page NAND uses last byte before ECC for BBI */

			oobregion->offset = 0;

			next--;

		}

	}

	oobregion->length = next - oobregion->offset;

	return 0;

}