gst/videobox/gstvideobox.c: Logic was reversed. Needs some  more fixes in the transform function to include AYUV output.

Original commit message from CVS:
* gst/videobox/gstvideobox.c: (gst_video_box_init),
(gst_video_box_transform_caps), (gst_video_box_set_caps):
Logic was reversed. Needs some  more fixes in the transform
function to include AYUV output.
Moved AYUV as prefered format.