video-anc: Fix gst_buffer_get_video_(afd|bar)_meta
The macros were not passing the meta GType to gst_buffer_get_meta,
rendering them unusable.
Also, the doc comments were specifying parameters meant for the
add_video_×_meta functions.
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The macros were not passing the meta GType to gst_buffer_get_meta,
rendering them unusable.
Also, the doc comments were specifying parameters meant for the
add_video_×_meta functions.