[nrf fromlist] dts: arm: nordic: Define power states for nrf54h20/cpuapp

Add definition of low power states 'idle' and 's2ram'
for nrf54h20/cpuapp.

Upstream PR: zephyrproject-rtos/zephyr#79098

Signed-off-by: Sebastian Głąb <sebastian.glab@nordicsemi.no>

dts/arm/nordic/nrf54h20_cpuapp.dtsi

@@ -57,3 +57,23 @@ wdt011: &cpuapp_wdt011 {};
 &grtc {
  interrupts = <109 NRF_DEFAULT_IRQ_PRIORITY>;
 };
+
+&cpus {
+ power-states {
+ idle: idle {
+ compatible = "zephyr,power-state";
+ power-state-name = "suspend-to-idle";
+ min-residency-us = <100000>;
+ };
+
+ s2ram: s2ram {
+ compatible = "zephyr,power-state";
+ power-state-name = "suspend-to-ram";
+ min-residency-us = <800000>;
+ };
+ };
+};
+
+&cpu {
+ cpu-power-states = <&idle &s2ram>;
+};