Cleanup Renderer::CalculateTargetSize(), and allow IRs higher than 4x to be set via ini.

Source/Core/VideoBackends/D3D/Render.cpp

@@ -1370,4 +1370,9 @@ void Renderer::SetInterlacingMode()
 	// TODO
 }
 
+int Renderer::GetMaxTextureSize()
+{
+	return DX11::D3D::GetMaxTextureSize();
+}
+
 }  // namespace DX11

Source/Core/VideoBackends/D3D/Render.h

@@ -49,6 +49,8 @@ public:
 	bool SaveScreenshot(const std::string &filename, const TargetRectangle &rc) override;
 
 	static bool CheckForResize();
+
+	int GetMaxTextureSize() override;
 };
 
 }