drm/i915/opregion: start using extended didl

Adding support for did2, or the extended support display devices ID
list, increases the total to 15.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>