drm/i915: Make pll functions take crtc_state, v2.

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

Changes since v1:
- Move vlv/chv changes and i9xx_set_pll_dividers changes
  from crtc_enable/disable patches to here.
- Add commit message.

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/20181004094604.2646-7-maarten.lankhorst@linux.intel.com