mtd: nand: ecc-mtk: Add ECC support fot MT7986 IC

Add ECC support fot MT7986 IC, and change err_mask value with
GENMASK macro.

Signed-off-by: Xiangsheng Hou <xiangsheng.hou@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230201021500.26769-6-xiangsheng.hou@mediatek.com