samples: fix nRF52840 sleep current

Modify low_power snippet to reduce sleep current.

Signed-off-by: Eduardo Montoya <[email protected]>

Author: edmont

samples/light_switch/snippets/low_power/boards/nrf52840dk_nrf52840.conf

@@ -0,0 +1,11 @@
+#
+# Copyright (c) 2025 Nordic Semiconductor
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+# Workaround for NCS 2.9.0/3.0.0
+# Uses kernel timer instead of dedicated timer2 to avoid 10µA sleep current increase
+# when timer2 is explicitly enabled in overlay files
+# TODO: Remove this when upgrading to NCS 3.1.0+
+CONFIG_ZIGBEE_TIME_KTIMER=y

samples/light_switch/snippets/low_power/snippet.yml

@@ -7,3 +7,8 @@
 name: low_power
 append:
   EXTRA_CONF_FILE: low_power.conf
+
+boards:
+  nrf52840dk/nrf52840:
+    append:
+      EXTRA_CONF_FILE: boards/nrf52840dk_nrf52840.conf