drm/i915/bios: Introduce has_ddi_port_info()

Pull the "do we want to use i915->vbt.ports[]?" check into
a central place.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211217155403.31477-2-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>