drm/i915: Fix VBT DSI DVO port handling

Turns out modern (icl+) VBTs still declare their DSI ports
as MIPI-A and MIPI-C despite the PHYs now being A and B.
Remap appropriately to allow the panels declared as MIPI-C
to work.

Cc: stable@vger.kernel.org
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8016
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230207064337.18697-2-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 118b5c13

)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>