packages: Fix gstreamer license
packages: Fix gstreamer license

It's LGPL2+, not LGPL. Matches recipes/custom.py now.

GStreamer/cerbero,atsushieno/cerbero,atsushieno/cerbero,nirbheek/cerbero,GStreamer/cerbero,GStreamer/cerbero,atsushieno/cerbero,GStreamer/cerbero,GStreamer/cerbero,atsushieno/cerbero,nirbheek/cerbero,nirbheek/cerbero,atsushieno/cerbero,nirbheek/cerbero