drm/i915: Populate encoder->devdata for g4x+ DP/HDMI ports

drm/i915: Populate encoder->devdata for g4x+ DP/HDMI ports

Let's make encoder->devdata (the VBT information for the port)
available on g4x+ platforms as well. Much easier when you can
just grab it there instead of trying to find it from some global
list array based on the port.

Note that (unlike DDI platforms) we don't currently require
that each DP/HDMI port is actually declared in VBT. Perhaps
in the future we may want to rethink that, but for now just
stick in a debug+FIXME as a reminder.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230208015508.24824-8-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>