[NXP][example][common][gn] Adding new GN file to reference openthread version from ot-nxp

Signed-off-by: Gatien Chapon <gatien.chapon@nxp.com>

Author: chapongatien

examples/platform/nxp/common/gn/args.gni

@@ -0,0 +1,21 @@
+# Copyright (c) 2023 Project CHIP Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import("//build_overrides/chip.gni")
+import("//build_overrides/openthread.gni")
+
+# Referencing openthread version from ot-nxp
+if (!(openthread_root == "")){
+  openthread_root = "${chip_root}/third_party/openthread/ot-nxp/openthread"
+}