Vulkan: Only use oldSwapchain in response to VK_ERROR_OUT_OF_DATE_KHR

Seems to be required on the latest NV driver, otherwise the presented
images are never shown.

Source/Core/VideoBackends/Vulkan/Renderer.h

@@ -81,7 +81,6 @@ private:
   void OnSwapChainResized();
   void BindEFBToStateTracker();
   void ResizeEFBTextures();
-  void ResizeSwapChain();
 
   void RecompileShaders();
   bool CompileShaders();