drm/i915: Pass crtc state to intel_pipe_{enable,disable}()

Get rid of the crtc->config usages from within
intel_pipe_{enable,disable}() by passing in the appropriate
crtc state.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171129153732.3612-3-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>