Fifo: rewrite sync on idle skipping hack

Now it's done without a busy loop

Source/Core/Core/CoreTiming.cpp

@@ -480,11 +480,8 @@ void Idle()
 		//When the FIFO is processing data we must not advance because in this way
 		//the VI will be desynchronized. So, We are waiting until the FIFO finish and
 		//while we process only the events required by the FIFO.
-		while (g_video_backend->Video_IsPossibleWaitingSetDrawDone())
-		{
-			ProcessFifoWaitEvents();
-			Common::YieldCPU();
-		}
+		ProcessFifoWaitEvents();
+		g_video_backend->Video_Sync();
 	}
 
 	idledCycles += DowncountToCycles(PowerPC::ppcState.downcount);