drm/i915/mtl: Meteorlake and later support DP 2.0

Meteorlake and newer platforms support DP 2.0.

Cc: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220817121948.180655-1-jani.nikula@intel.com