drm/i915: move intel_crtc->fdi_lanes to pipe_config

We need this for two reasons:
- Correct handling of shared fdi lanes on ivb with fastboot.
- Handling fdi link bw limits when we only have two fdi lanes by
  dithering down a bit.

Just search&replace in this patch, no functional change at all.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>