Migrate to QSurfaceFormat::setDefaultFormat()

setDefaultFormat() is being moved form QQuickWindow to QSurfaceFormat.

Change-Id: Id76c2c332c837e2e988a2e8f4da2975065938e32
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>