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

arch/arm64/boot/dts/qcom/sm8450.dtsi

@@ -2277,8 +2277,8 @@ remoteproc_mpss: remoteproc@4080000 {
 			clocks = <&rpmhcc RPMH_CXO_CLK>;
 			clock-names = "xo";
 
-			power-domains = <&rpmhpd 0>,
-					<&rpmhpd 12>;
+			power-domains = <&rpmhpd SM8450_CX>,
+					<&rpmhpd SM8450_MSS>;
 			power-domain-names = "cx", "mss";
 
 			memory-region = <&mpss_mem>;