AVIDump: Drop stored frame.

This used an invalid pointer, which was only valid within AddFrame.

This drops a feature which shall dump the last frame as it might was dropped before.
A good implementation however should "overwrite" the last frame if the time matches.
But this needs to delay every frame a bit.

Source/Core/VideoCommon/AVIDump.h

@@ -12,7 +12,6 @@ private:
   static bool CreateFile();
   static void CloseFile();
   static void CheckResolution(int width, int height);
-  static void StoreFrameData(const u8* data, int width, int height, int stride, u64 ticks);
 
 public:
   static bool Start(int w, int h);