SPU2-X:2635
This fixes Fatal Frame 2 (and likely 3 as well). A really long standing bug we had
SPU2-X:r2638
I guess I should've tried this from the beginning. Actually, I did, but it
wasn't quite the same code and rama benchmarked it instead of me. Other
optimisations are irrelevant, speed is now within measuring error of r2634, I
feel like an idiot.