[GPU] Set frame buffer texture size to window size

Ryujinx/Ui/GLScreen.cs

@@ -38,6 +38,8 @@ namespace Ryujinx
         protected override void OnLoad(EventArgs e)
         {
             VSync = VSyncMode.On;
+
+            Renderer.SetWindowSize(Width, Height);
         }
 
         protected override void OnUpdateFrame(FrameEventArgs e)
@@ -173,8 +175,6 @@ namespace Ryujinx
         {
             Ns.Statistics.StartSystemFrame();
 
-            GL.Viewport(0, 0, Width, Height);
-
             Title = $"Ryujinx Screen - (Vsync: {VSync} - FPS: {Ns.Statistics.SystemFrameRate:0} - Guest FPS: " +
                 $"{Ns.Statistics.GameFrameRate:0})";