arm64: dts: mediatek: mt8186: add default thermal zones

Inspired by the vendor kernel but adapted to the upstream thermal
driver version.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Signed-off-by: Julien Panis <jpanis@baylibre.com>
Link: https://lore.kernel.org/r/20240603-mtk-thermal-mt818x-dtsi-v7-4-8c8e3c7a3643@baylibre.com


Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>