Small improve in scemp4 part 2

I added a hack
u32 sceMp4AacDecode(...)
return -1;
Now Speedball 2 Evolution in-game.
![1](https://cloud.githubusercontent.com/assets/2177532/3124503/08f158b2-e77e-11e3-9a53-c23060239d1e.jpg)
The game still have sound.