Workaround the mp3 sound hack

It is by observation the difference between various titles which uses mp3 on the return LoopNum so i treated it as workaround. All other titles will always return -1 for loopNum while DOA return 0 instead . 

As always , we may need test later to see how real PSP handle this case.

@sum2012 / @solarmystic can help to test a bit.