rro_overlays: Redo TetheringOverlay's blueprint

This now matches WifiOverlay.

Change-Id: I9e4e859b7aca75d41556ea5807e34a4eb4598266
Signed-off-by: Chenyang Zhong <zhongcy95@gmail.com>
Signed-off-by: DennySPb <dennyspb@gmail.com>

rro_overlays/TetheringOverlay/Android.bp

@@ -1,22 +1,7 @@
-//
-// Copyright (C) 2020 The Android Open-Source Project
-//
-// 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.
-//
-
 runtime_resource_overlay {
     name: "TetheringConfigOverlay",
-    resource_dirs: ["res"],
+    theme: "TetheringConfigOverlay",
+    certificate: "platform",
     sdk_version: "current",
-    proprietary: true
+    product_specific: true
 }