DP sink specific quirks
* tag 'topic/dp-quirks-2017-05-31' of git://anongit.freedesktop.org/git/drm-intel:
drm/i915: Detect USB-C specific dongles before reducing M and N
drm/dp: start a DPCD based DP sink/branch device quirk database
drm/i915: use drm DP helper to read DPCD desc
drm/dp: add helper for reading DP sink/branch device desc from DPCD