gstavviddec: only set range when actually reported by avcodec
otherwise we get incomplete colorimetry that video-info complains about
I noticed I'm getting following warnings after upgrade:
video-info.c: Need to specify a color matrix when using YUV format (I420_10LE)
the reason is that if gstavdec doesn't get colorimetry from ffmpeg, it makes up an incomplete one by setting just the color range to an arbitrary value.
Patch correctes it by only setting color range when provided from ffmpeg.
Edited by Matej