cerbero: Fix typo in license install function
cerbero: Fix typo in license install function

We need to return an empty array instead of None, else we will fail
during installation trying to use a file path called None

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