Atrac: Move currentSample on finish.

This seems to be what happens, and allows remaining frames to calculate
properly in some cases where it wasn't before.

Core/HLE/sceAtrac.cpp

@@ -1090,6 +1090,10 @@ u32 _AtracDecodeData(int atracID, u8 *outbuf, u32 outbufPtr, u32 *SamplesNum, u3
 				}
 			} else if (hitEnd) {
 				finishFlag = 1;
+
+				// Still move forward, so we know that we've read everything.
+				// This seems to be reflected in the context as well.
+				atrac->currentSample += atrac->samplesPerFrame();
 			}
 
 			*finish = finishFlag;