drm/i915: Fix dg1 buf trans tables

For some reason the dg1 buf trans tables have been stuffed into
icl_get_combo_buf_trans_edp() which doesn't even get called
on dg1. Split them out into a proper dg1 specific function,
and also make sure we use the proper buf trans tables for
DP as well as eDP.

v2: Add the hobl stuff

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210608073603.2408-13-ville.syrjala@linux.intel.com