stagefright: Fix audio codec fallthru

 * We shouldn't return an error from setAudioFormat unless it's
   really an error since fallthru is necessary.
 * We don't even need to do this, since the component name is
   checked before calling into mm-parser or FFMPEG.
 * Fixes Vorbis decoding after FFMPEG patch.

Change-Id: I4871c62044c6693e5698119dee3a10c20c26e2c7
stagefright: Remove wrongly ifdeffed parsing code

 * This code was actually meant to depend on FFMPEG, not QCOM, as
   it enables support for several additional codecs.
 * These are now defined in Stagefright now that FFMPEG is in.

Change-Id: I6f22c185e84176201d7e5f90a92e1b4a26008efd