arm64: dts: qcom: sc8280xp-x13s: Add thermal zone support

Add thermal zone support by making use of the thermistor SYS_THERM6.
Based on experiments, this thermistor seems to reflect the actual
surface temperature of the laptop.

For the cooling device, all BIG CPU cores are throttled down to keep the
temperature at a sane level.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221103095810.64606-13-manivannan.sadhasivam@linaro.org