decoder: vc1: Fail only on actual interlaced frames
decoder: vc1: Fail only on actual interlaced frames

In the earlier patch:

 f31d9f3 decoder: vc1: Print error on interlaced content

Decoding would error out if the interlace flag was set in the
sequence bdu. This isn't quite right because a video can have this
flag set and yet not have any interlaced pictures.

Here instead we error out when either parsing a field bdu or
decoding a frame bdu which has fcm set to anything other than
progressive.

Signed-off-by: Scott D Phillips <scott.d.phillips@intel.com>

https://bugzilla.gnome.org/show_bug.cgi?id=769250

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