drm/i915: Don't display the boot CDCLK twice

intel_update_cdclk() will already display the boot CDCLK for DDI
platforms, no need to repeat there.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>