drm/i915: move skl_preferred_vco_freq to display substruct

The info is related to display, and should be placed under
i915->display.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/4e9877d1641bce905cc9dd5eabe40df51ddbe9b5.1712599670.git.jani.nikula@intel.com
4 files changed