Fifo: rewrite sync on idle skipping hack

Now it's done without a busy loop

Source/Core/VideoBackends/Software/VideoBackend.h

@@ -45,7 +45,7 @@ class VideoSoftware : public VideoBackend
 	void Video_SetRendering(bool bEnabled) override;
 
 	void Video_GatherPipeBursted() override;
-	bool Video_IsPossibleWaitingSetDrawDone() override;
+	void Video_Sync() override {}
 
 	void RegisterCPMMIO(MMIO::Mapping* mmio, u32 base) override;