UI: When stepping, clear on initial load.

Otherwise we get the UI rather than a black screen.

UI/EmuScreen.cpp

@@ -989,7 +989,7 @@ void EmuScreen::preRender() {
 	bool useBufferedRendering = g_Config.iRenderingMode != FB_NON_BUFFERED_MODE;
 	if ((!useBufferedRendering && !g_Config.bSoftwareRendering) || Core_IsStepping()) {
 		// We need to clear here already so that drawing during the frame is done on a clean slate.
-		if (Core_IsStepping()) {
+		if (Core_IsStepping() && gpuStats.numFlips != 0) {
 			draw->BindFramebufferAsRenderTarget(nullptr, { RPAction::KEEP, RPAction::DONT_CARE });
 		} else {
 			draw->BindFramebufferAsRenderTarget(nullptr, { RPAction::CLEAR, RPAction::CLEAR, 0xFF000000 });