[nrf fromlist] boards: Define pm_s2ram_stack for nRF54H20

Add the definition of pm_s2ram_stack memory region for nRF54H20.

Upstream PR #: 95914

Signed-off-by: Tomasz Chyrowicz <[email protected]>
(cherry picked from commit c274834)

Author: tomchy

boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpuapp.dts

@@ -356,6 +356,13 @@ zephyr_udc0: &usbhs {
 			zephyr,memory-region = "PMLocalRamfunc";
 		};
 
+		/* temporary stack for S2RAM resume logic */
+		pm_s2ram_stack: cpuapp_s2ram_stack@22007fd0 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x22007fd0 16>;
+			zephyr,memory-region = "pm_s2ram_stack";
+		};
+
 		/* run-time common S2RAM cpu context RAM */
 		pm_s2ram: cpuapp_s2ram@22007fe0  {
 			compatible = "zephyr,memory-region", "mmio-sram";