drm/i915: copy staged scaler state from drm state to crtc->config.

This is required for commit to perform as per staged assignment
of scalers until atomic crtc commit function is available.

As a place holder doing this copy from intel_atomic_commit for
scaling to operate correctly.

Signed-off-by: Chandra Konduru <chandra.konduru@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>