drm/i915/bios: get rid of vbt ddi_port_info

We can finally remove the extra caching in ddi_port_info. Good riddance.

v2: Rebased

Cc: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/f56e864d10bb3cbe616288450d92b56325d1df12.1630512523.git.jani.nikula@intel.com