drm/dp: add DPCD definitions from eDP 1.2
drm/dp: add DPCD definitions from eDP 1.2

Mostly display control related DPCD addresses.

Signed-off-by: Jani Nikula <ba783f3beccaedfda693f41a15407d612a629408@intel.com>
Reviewed-by: Sonika Jindal <cd61f9fbc6d7aeabe3269febf35c0efd90c23268@intel.com>
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs