Add XML for pro audio feature

Bug: 23604253
Change-Id: I480cf0a46c286badc6fd95a3b42e6cb1ed056b1b

data/etc/android.hardware.audio.pro.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2015 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.
+-->
+
+<!-- This is the feature indicating professional audio, as specified by the
+     CDD. ONLY devices that meet the CDD's requirements may declare this
+     feature. -->
+<permissions>
+    <feature name="android.hardware.audio.pro" />
+</permissions>