arm64: dts: qcom: sc7280-idp: correct ADC channel node name and unit address

Correct SPMI PMIC VADC channel node name:
1. Use hyphens instead of underscores,
2. Add missing unit address.

This fixes `make dtbs_check` warnings like:

  qcom/sc7280-idp.dtb: pmic@0: adc@3100: 'pmk8350_die_temp', 'pmr735a_die_temp' do not match any of the regexes: '^.*@[0-9a-f]+$', 'pinctrl-[0-9]+'

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220828084341.112146-12-krzysztof.kozlowski@linaro.org