Fix a Javadoc to clarify when setAudioStreamType() should be called.

 *     <td>{Idle, Initialized, Stopped, Prepared, Started, Paused,

 *          PlaybackCompleted}</p></td>

 *     <td>{Error}</p></td>

 *     <td>Successful invoke of this method does not change the state.</p></td></tr>

 *     <td>Successful invoke of this method does not change the state. In order for the

 *         target audio stream type to become effective, this method must be called before

 *         prepare() or prepareAsync().</p></td></tr>

 * <tr><td>setDataSource </p></td>

 *     <td>{Idle} </p></td>

 *     <td>{Initialized, Prepared, Started, Paused, Stopped, PlaybackCompleted,

    /**

     * Sets the audio stream type for this MediaPlayer. See {@link AudioManager}

     * for a list of stream types.

     * for a list of stream types. Must call this method before prepare() or

     * prepareAsync() in order for the target stream type to become effective

     * thereafter.

     *

     * @param streamtype the audio stream type

     * @see android.media.AudioManager