Add ADC and thermal monitor configuration for skin temperature,
plus a thermal zone that monitors the skin temperature and uses
the big cores as cooling devices.

CoachZ rev1 is stuffed with an incompatible thermistor for the
skin temperature, disable the thermal zone for rev1 to avoid
the use of bogus temperature values.
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Link: https://lore.kernel.org/r/20210414111007.v1.1.I1a438604a79025307f177347d45815987b105cb5@changeidSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>