drm: document standard connector properties

There's a really big pile of additional connector properties, a lot of
them standardized. But they're all for specific outputs (panels, TV,
scaling, ...) so I left them out for now since this is enough for a
start.

I typed this to give Manasi a place to add her new link status
property documentation.

v2: forgot to git add all the bits (Manasi).

v3: Be more epxlicit about integrated tiled panels (Archit)

Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Archit Taneja <architt@codeaurora.org>
Reviewed-by: Archit Taneja <architt@codeaurora.org>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161117085648.26646-1-daniel.vetter@ffwll.ch