AVFoundation: Remove QVideoSurfaceCoreGraphicsPainter

This was a leftover from Qt 4, as it is no longer possible to use the
CoreGraphics paint engine.  Instead we should just use the logic in
QPainterVideoSurface render the QVideoFrame.

Change-Id: I7e97fe7c30fd478dcd405d300e0c3f70050ca25f
Reviewed-by: Christian Stromme <christian.stromme@digia.com>