fix ffmpeg audio decoder crash when NuPlayer

You should sync code:
git://github.com/CyanogenMod/android_frameworks_av  branch: cm_maguro-10.2

commit fb76cda8cd6a7dd7bca015105684210b5d757d71
Author: Michael Chen <omxcodec@gmail.com>
Date:   Fri Jul 25 00:43:55 2014 +0800

    fix setMP3Format and setWMAFormat

    Change-Id: Ica1e51b1a8baf5ac88b897489ddb404e85d24e33