arm64: dts: qcom: sc8280xp-pmics: Define adc for temp-alarms

sc8280xp-pmics define the two thermal zones "pm8280-1-thermal" and
"pm8280-2-thermal", but the related temp-alarm instances are not tied to
any adc channels, and as such continuously report the bogus temperature
of 37C.

After previously defining these adc channels across all boards using
sc8280xp-pmics.dtsi, we can now add these references.

This does however mean that we have a non-disabled node referencing
default-disabled nodes, requiring each board to enable the pmk8280_vadc.
Avoid this by marking pmk8280_vadc okay.

Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20240210-sc8280xp-pmic-thermal-v1-2-a1c215a17d10@quicinc.com


Signed-off-by: Bjorn Andersson <andersson@kernel.org>