config.xml: Grant deviceKeyHandler role for config_deviceKeyHandler

    <string name="config_systemCallStreaming" translatable="false"></string>

    <!-- The name of the package that will hold the default retail demo role. -->

    <string name="config_defaultRetailDemo" translatable="false"></string>

    <!-- The name of the package that will hold the default device keyhandler role. -->

    <string name="config_deviceKeyHandler" translatable="false"></string>

    <!-- The component name of the wear service class that will be started by the system server. -->

    <string name="config_wearServiceComponent" translatable="false"></string>