Fix incorrect handling of auto IR

Some lines of code in Dolphin just plainly grabbed the value of
g_ActiveConfig.iEFBScale, which resulted in Auto being treated as
0x rather than the actual automatically selected scale.

Source/Core/VideoCommon/RenderBase.cpp

@@ -131,6 +131,11 @@ void Renderer::RenderToXFB(u32 xfbAddr, const EFBRectangle& sourceRc, u32 fbStri
   }
 }
 
+unsigned int Renderer::GetEFBScale() const
+{
+  return m_efb_scale;
+}
+
 int Renderer::EFBToScaledX(int x) const
 {
   return x * static_cast<int>(m_efb_scale);