gst1-vaapi: bump version to 1.12.0

0001 patch already included in this release:
  https://github.com/GStreamer/gstreamer-vaapi/commit/159e3c3f08ef1c19da4ede8a437337dd8cf7f0b7
0002 patch already included in this release:
  https://github.com/GStreamer/gstreamer-vaapi/commit/152217064f1192bb836620ad7eaadbc031624f4c



Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>