dt-bindings: iio: adc: qcom,spmi-adc7: use predefined channel ids

Each of qcom,spmi-adc7-pm*.h headers define a set of ADC channels that
can be used for monitoring on thie particular chip. Switch them to use
channel IDs defined in the dt-bindings/iio/qcom,spmi-vadc.h header
instead of specifying the numeric IDs.

Suggested-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230707123027.15107230

-2-dmitry.baryshkov@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>