dts: arm: stm32wba: add standby mode to device tree

Add standby mode to device tree

Signed-off-by: Guillaume Gautier <[email protected]>

Author: gautierg-st

dts/arm/st/wba/stm32wba.dtsi

@@ -22,6 +22,7 @@
 	chosen {
 		zephyr,entropy = &rng;
 		zephyr,flash-controller = &flash;
+		st,lptim-stdby-timer = &rtc;
 	};
 
 	cpus {
@@ -32,7 +33,7 @@
 			device_type = "cpu";
 			compatible = "arm,cortex-m33";
 			reg = <0>;
-			cpu-power-states = <&stop0 &stop1>;
+			cpu-power-states = <&stop0 &stop1 &standby>;
 			#address-cells = <1>;
 			#size-cells = <1>;
 
@@ -55,6 +56,13 @@
 				substate-id = <2>;
 				min-residency-us = <500>;
 			};
+			standby: state2 {
+				compatible = "zephyr,power-state";
+				power-state-name = "suspend-to-ram";
+				substate-id = <1>;
+				min-residency-us = <1000>;
+				exit-latency-us = <50>;
+			};
 		};
 	};