Direct2D QPA: Disable vsync

We shouldn't block the whole gui thread for vsyncing. This can slow things
down a lot if a lot of drawing happens.

Change-Id: Ie459f9dee2271e7908e2b7f56873393c67f82836
Reviewed-by: Risto Avila <risto.avila@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>

src/plugins/platforms/direct2d/qwindowsdirect2dwindow.cpp

@@ -128,7 +128,7 @@ void QWindowsDirect2DWindow::flush(QWindowsDirect2DBitmap *bitmap, const QRegion
     }
 
     m_bitmap->deviceContext()->end();
-    m_swapChain->Present(1, 0);
+    m_swapChain->Present(0, 0);
 }
 
 void QWindowsDirect2DWindow::resizeSwapChain(const QSize &size)