arm64: dts: qcom: sm8450: Use defines for power domain indices

Use the defines from qcom-rpmpd.h instead of bare numbers for
readability.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221115130936.6830-1-konrad.dybcio@linaro.org