[nrf fromlist] samples: boards: nordic: system_off: Enable nrf54lm20b.

Enable sample for nrf54lm20dk/nrf54lm20b/cpuapp target.

Signed-off-by: Bartlomiej Buczek <bartlomiej.buczek@nordicsemi.no>

Upstream PR #: 104594

Author: nordic-babu

samples/boards/nordic/system_off/boards/nrf54lm20dk_nrf54lm20_a_b_cpuapp.dtsi

@@ -0,0 +1,25 @@
+/ {
+	cpuapp_sram@2007ec00 {
+		compatible = "zephyr,memory-region", "mmio-sram";
+		reg = <0x2007ec00 DT_SIZE_K(4)>;
+		zephyr,memory-region = "RetainedMem";
+		status = "okay";
+
+		retainedmem0: retainedmem {
+			compatible = "zephyr,retained-ram";
+			status = "okay";
+		};
+	};
+
+	aliases {
+		retainedmemdevice = &retainedmem0;
+	};
+};
+
+&cpuapp_sram {
+	/* Shrink SRAM size to avoid overlap with retained memory region:
+	 * 511 - 4 = 507KB = 0x7ec00
+	 */
+	reg = <0x20000000 DT_SIZE_K(507)>;
+	ranges = <0x0 0x20000000 0x7ec00>;
+};

samples/boards/nordic/system_off/boards/nrf54lm20dk_nrf54lm20a_cpuapp.overlay

@@ -1,25 +1 @@
-/ {
-	cpuapp_sram@2007ec00 {
-		compatible = "zephyr,memory-region", "mmio-sram";
-		reg = <0x2007ec00 DT_SIZE_K(4)>;
-		zephyr,memory-region = "RetainedMem";
-		status = "okay";
-
-		retainedmem0: retainedmem {
-			compatible = "zephyr,retained-ram";
-			status = "okay";
-		};
-	};
-
-	aliases {
-		retainedmemdevice = &retainedmem0;
-	};
-};
-
-&cpuapp_sram {
-	/* Shrink SRAM size to avoid overlap with retained memory region:
-	 * 511 - 4 = 507KB = 0x7ec00
-	 */
-	reg = <0x20000000 DT_SIZE_K(507)>;
-	ranges = <0x0 0x20000000 0x7ec00>;
-};
+#include "nrf54lm20dk_nrf54lm20_a_b_cpuapp.dtsi"

samples/boards/nordic/system_off/boards/nrf54lm20dk_nrf54lm20b_cpuapp.overlay

@@ -0,0 +1 @@
+#include "nrf54lm20dk_nrf54lm20_a_b_cpuapp.dtsi"

samples/boards/nordic/system_off/sample.yaml

@@ -15,6 +15,7 @@ tests:
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
       - nrf7120dk/nrf7120/cpuapp
     harness: console
     harness_config:
@@ -35,6 +36,7 @@ tests:
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
       - nrf7120dk/nrf7120/cpuapp
     extra_configs:
       - CONFIG_APP_USE_RETAINED_MEM=y
@@ -55,6 +57,7 @@ tests:
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
       - nrf7120dk/nrf7120/cpuapp
     extra_configs:
       - CONFIG_SYS_CLOCK_DISABLE=y
@@ -73,6 +76,7 @@ tests:
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
       - nrf7120dk/nrf7120/cpuapp
     extra_configs:
       - CONFIG_APP_USE_RETAINED_MEM=y
@@ -95,6 +99,7 @@ tests:
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
       - nrf7120dk/nrf7120/cpuapp
     extra_configs:
       - CONFIG_GRTC_WAKEUP_ENABLE=y
@@ -120,6 +125,7 @@ tests:
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
       - nrf7120dk/nrf7120/cpuapp
     extra_configs:
       - CONFIG_APP_USE_RETAINED_MEM=y