added xiao nrf54l15 support for otbr

prj.conf

@@ -0,0 +1,24 @@
+#
+# Copyright (c) 2020 Nordic Semiconductor
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+# Enable OpenThread
+CONFIG_OPENTHREAD=y
+
+# Set OpenThread NCP architecture
+CONFIG_OPENTHREAD_COPROCESSOR=y
+CONFIG_OPENTHREAD_COPROCESSOR_RCP=y
+
+# Nordic feature set
+CONFIG_OPENTHREAD_NORDIC_LIBRARY_RCP=y
+
+# Increase Settings storage size
+CONFIG_PM_PARTITION_SIZE_SETTINGS_STORAGE=0x8000
+
+# Disable RTT
+CONFIG_USE_SEGGER_RTT=n
+
+# Disable GPIO
+CONFIG_GPIO=n