drm/i915: Make ironlake_pch_transcoder_set_timings take crtc_state

Instead of passing crtc and dereferencing crtc->config,
pass the correct crtc_state and obtain the crtc pointer from there.

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/20181004094604.2646-8-maarten.lankhorst@linux.intel.com