thermal: mediatek: add Mediatek thermal driver for mt2712

This patch adds support for mt2712 chip to mtk_thermal,
and integrate mt2712 into the same mediatek thermal driver.
MT2712 has only 1 bank and 4 sensors.

Signed-off-by: Louis Yu <louis.yu@mediatek.com>
Reviewed-by: Dawei Chien <dawei.chien@mediatek.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>