GStreamer's backend does not implements this features, therefore now is used the V4L2 interface for the contrast, saturation, brightness and the sharpening adjustments. The V4l2 interface works together with the GStreamer and covers the features which are not supported by the GStreamer. Change-Id: I995ed6cb096a29543fb80206384a92c13a1d1af2 Reviewed-by: Yoann Lopes <yoann.lopes@theqtcompany.com>