Revert "Eliminate the "productivity_device" setting."

This reverts commit d0a0fc2cd1.

Missed a use. Prema-revert.

Change-Id: I6bce595646e2e2bf1e506388a2da9e1cd8f61a09

packages/DocumentsUI/AndroidManifest.xml

@@ -54,7 +54,8 @@
             android:name=".LauncherActivity"
             android:theme="@android:style/Theme.NoDisplay"
             android:icon="@drawable/ic_files_app"
-            android:label="@string/files_label">
+            android:label="@string/files_label"
+            android:enabled="@bool/productivity_device">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />

packages/DocumentsUI/res/values/config.xml

@@ -18,6 +18,7 @@
     <!-- Allow Advanced Devices default value to be customised -->
     <bool name="config_defaultAdvancedDevices">false</bool>
 
+    <bool name="productivity_device">true</bool>
     <!-- Intentionally unset. Vendors should set this in an overlay. -->
     <string name="trusted_quick_viewer_package"></string>
 </resources>