Fixes #11432.  Remove a now-unnecessary scaling operation.

H264Parser::frameRate() was modified in
5ccedb61ddd2fa87b426cd1c0fbc43d2645cb9a55ccedb61ddd2fa87b426 to return
frames per second instead of frames per thousand seconds, but the one
remaining call to frameRate() was still trying to convert to frames
per second.  This caused big problems in the AVSync mechanism.