drm/i915: Make panel fitter functions take state

If we look at the correct state instead of crtc->config, we can nuke the
force parameter, and we cleanup a few more users of crtc->config at the
same time.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181004094604.2646-3-maarten.lankhorst@linux.intel.com