vaapipostproc: update filters at color balance
vaapipostproc: update filters at color balance

This is a fix for a regression of previous commit, which updates the filters
only when the property is set, because it is also required to update the
filter when the color balance interface change its values.

ceyusa/gstreamer-vaapi,GStreamer/gstreamer-vaapi,GStreamer/gstreamer-vaapi,ceyusa/gstreamer-vaapi