[API CHANGE] Do not include framerate field in videoinfo of audio files

Do not include the framerate property for the derivatives part of
the output on audio files in query=videoinfo&viprop=derivatives.

This makes the output of derivative sound files be consistent
with what is outputted for the original sound file.

Change-Id: I58fd36fe3a8bb6aec94881913b7a9cc5a2f37391
Merge "[API CHANGE] Do not include framerate field in videoinfo of audio files"