samples: nfc: system_off: Optimize power consumption for nRF54LM

Add board configuration for nRF54LM20DK
Enabling PM_DEVICE and PM_DEVICE_RUNTIME

Ref: KRKNWK-21307

Signed-off-by: Dawid Przybylo <[email protected]>

Author: dawidprzybylo

samples/nfc/system_off/boards/nrf54lm20dk_nrf54lm20a_cpuapp.conf

@@ -0,0 +1,8 @@
+#
+# Copyright (c) 2026 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+CONFIG_PM_DEVICE=y
+CONFIG_PM_DEVICE_RUNTIME=y

samples/nfc/system_off/boards/nrf54lm20dk_nrf54lm20a_cpuapp.overlay

@@ -0,0 +1,9 @@
+/*
+ * Copyright (c) 2026 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+&uart20 {
+	zephyr,pm-device-runtime-auto;
+};