drm/i915: Pass pipe_config to pch_enable() functions

Using crtc->config directly is being removed in favor of passing a
pipe_config. Follow the trend and pass pipe_config to pch_enable()
functions.

v2: s/pipe_config/crtc_state/ (Ville)
  - constify crtc_state. (Ville)
  - take crtc from crtc_state. (Ville)
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170302125857.14665-4-ander.conselvan.de.oliveira@intel.com