playbin: read the initial state of internal color balance interface

Submitted by Ung, Teng En

Link to original bug (#787973)

Description

In linux with gstreamer 1.8.3, when try using playbin and assign the color balance with video-sink. The value got reset to other value.

Run the test with gstreamer vaapi, when we don't use playbin the color balance value will apply :-
gst-launch-1.0 filesrc location=<Video> ! qtdemux ! queue ! h264parse ! vaapidecode ! queue ! vaapisink hue=180

But when use playbin and change the video-sink to include color balance value; it will be reset to default :-
gst-launch-1.0 playbin2 uri=<Video> video-sink="vaapisink hue=180"

Version: 1.12.3