drm/i915: ILK, SNB and IVB don't have linetime watermarks

So don't call intel_update_linetime_watermarks from
ironlake_crtc_mode_set. Only Haswell has these watermarks.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>