boards: nordic: Add boot mode chosen nodes

Adds boot mode chosen nodes to the nrf5340dk, nrf52840dk and
nrf54l15dk boards

Signed-off-by: Jamie McCrae <[email protected]>

Author: nordicjm

boards/nordic/nrf52840dk/nrf52840dk_nrf52840.dts

@@ -21,6 +21,7 @@
 		zephyr,bt-mon-uart = &uart0;
 		zephyr,bt-c2h-uart = &uart0;
 		zephyr,ieee802154 = &ieee802154;
+		zephyr,boot-mode = &boot_mode0;
 	};
 
 	leds {
@@ -276,3 +277,13 @@ zephyr_udc0: &usbd {
 	compatible = "nordic,nrf-usbd";
 	status = "okay";
 };
+
+&gpregret1 {
+	status = "okay";
+
+	boot_mode0: boot_mode@0 {
+		compatible = "zephyr,retention";
+		status = "okay";
+		reg = <0x0 0x1>;
+	};
+};

boards/nordic/nrf5340dk/nrf5340dk_nrf5340_cpuapp.dts

@@ -18,5 +18,16 @@
 		zephyr,code-partition = &slot0_partition;
 		zephyr,sram-secure-partition = &sram0_s;
 		zephyr,sram-non-secure-partition = &sram0_ns;
+		zephyr,boot-mode = &boot_mode0;
+	};
+};
+
+&gpregret1 {
+	status = "okay";
+
+	boot_mode0: boot_mode@0 {
+		compatible = "zephyr,retention";
+		status = "okay";
+		reg = <0x0 0x1>;
 	};
 };

boards/nordic/nrf54l15dk/nrf54l_05_10_15_cpuapp_common.dtsi

@@ -18,6 +18,7 @@
 		zephyr,flash-controller = &rram_controller;
 		zephyr,flash = &cpuapp_rram;
 		zephyr,ieee802154 = &ieee802154;
+		zephyr,boot-mode = &boot_mode0;
 	};
 };
 
@@ -91,6 +92,16 @@
 	status = "okay";
 };
 
+&gpregret1 {
+	status = "okay";
+
+	boot_mode0: boot_mode@0 {
+		compatible = "zephyr,retention";
+		status = "okay";
+		reg = <0x0 0x1>;
+	};
+};
+
 &spi00 {
 	status = "okay";
 	cs-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>;