arm64: dts: qcom: sa8775p: Clean up the PSCI PDs

Because SA8775P comes with two disjoint CPU clusters, we have to follow
a similar topology description like the one in sm8750.dtsi, so:

system_pd
	cluster0_pd
		cpu_pd0
		...
	cluster1_pd
		cpu_pd4
		...

Do that & wire it up to APPS RSC to make the bindings checker happy.

Signed-off-by: Konrad Dybcio <[email protected]>
Reviewed-by: Dmitry Baryshkov <[email protected]>
Link: https://lore.kernel.org/r/20250327-topic-more_dt_bindings_fixes-v2-11-b763d958545f@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <[email protected]>

Author: quic-kdybcio

arch/arm64/boot/dts/qcom/sa8775p.dtsi

@@ -471,17 +471,17 @@
 
 		cluster_0_pd: power-domain-cluster0 {
 			#power-domain-cells = <0>;
-			power-domains = <&cluster_2_pd>;
 			domain-idle-states = <&cluster_sleep_gold>;
+			power-domains = <&system_pd>;
 		};
 
 		cluster_1_pd: power-domain-cluster1 {
 			#power-domain-cells = <0>;
-			power-domains = <&cluster_2_pd>;
 			domain-idle-states = <&cluster_sleep_gold>;
+			power-domains = <&system_pd>;
 		};
 
-		cluster_2_pd: power-domain-cluster2 {
+		system_pd: power-domain-system {
 			#power-domain-cells = <0>;
 			domain-idle-states = <&cluster_sleep_apss_rsc_pc>;
 		};
@@ -5484,6 +5484,7 @@
 					  <WAKE_TCS 3>,
 					  <CONTROL_TCS 0>;
 			label = "apps_rsc";
+			power-domains = <&system_pd>;
 
 			apps_bcm_voter: bcm-voter {
 				compatible = "qcom,bcm-voter";