drm/i915: WARN if a port should use VBT provided vswing tables

drm/i915: WARN if a port should use VBT provided vswing tables

We don't parse the VBT vswing/preemphassis tables at all currently.
Let's WARN if a port wants to use them so we get a heads up that
whether we really need to implement this stuff or not. My
current stash contains no VBTs with this bit set.

v2: Move to print_ddi_port() (Jani)

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220916204132.10469-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>