omxil: Remove a few audio codec mappings

omxil: Remove a few audio codec mappings

This reverts most of 2b101ff4a0.

VLC_CODEC_MP3 seems to work fine with multiple OMX mp3 decoders,
so keep it mapped.

VLC_CODEC_MPGA does work with some OMX mp3 decoders (OMX.SEC.mp3.dec
seems to handle it) but not with all (OMX.google.mp3.decoder doesn't
seem to handle it).

Vorbis does not work with OMX decoders in the current form. The only
such decoder I've seen is OMX.google.vorbis.decoder, and using it
requires us to modify the packets sent a little. Even if this can be
done pretty easily, the packet format feels more like an android
internal hack than an official spec of any sort, so disable this
mapping since there isn't much value in using it currently.

WMA does not work with OMX in the current form (tested with
OMX.SEC.wma.dec). I've got work in progress code that makes certain
WMA files work with it, but not all, so disable it until at least
most of them work properly.