drm: add connector info/property for non-desktop displays [v2]

This adds the infrastructure needed to quirk displays
using edid and to mark them a non-desktop.

A non-desktop display is one which shouldn't normally be included
as a part of a desktop environment.

This is meant to cover head mounted devices like HTC Vive.

v2: Change description from non-standard to non-desktop, add docs

Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

fixup docs