Qt: fix input focus checks being wrong

When rendering to main and going full screen, we aren't using the main window handle
as the code assumed, but the other, detached, render widget.

Source/Core/DolphinQt/Host.cpp

@@ -88,7 +88,7 @@ bool Host::GetRenderFocus()
 #ifdef _WIN32
   // Unfortunately Qt calls SetRenderFocus() with a slight delay compared to what we actually need
   // to avoid inputs that cause a focus loss to be processed by the emulation
-  if (m_render_to_main)
+  if (m_render_to_main && !m_render_fullscreen)
     return GetForegroundWindow() == (HWND)m_main_window_handle.load();
   return GetForegroundWindow() == (HWND)m_render_handle.load();
 #else