linux-phytec-fsl

drm/i915: extract modeset config save/restore code

At the end this won't be of much use to us, but meanwhile just extract
it to get a better overview of what exactly set_config does.

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>