drm/doc: document all the properties in drm_mode_config

drm/doc: document all the properties in drm_mode_config

I'm fed up with the warning noise from kernel-doc.

Aside: I stumbled over dirty_info_property, which is only set by udl
and qxl. But we have a _lot_ more drivers implementing a dirty
callback on framebuffers. Not entirely sure what the ABI is supposed
to be here, but it seems confusing for sure.

Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1468612088-9721-3-git-send-email-daniel.vetter@ffwll.ch