CameraBrowser: Give it ACCESS_USB permission, which is now required for PTP

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.android.camerabrowser">

    <uses-permission android:name="android.permission.ACCESS_USB" />

    <application android:label="@string/app_label">

        <activity android:name="CameraBrowser" android:label="Camera Browser">

            <intent-filter>