bunch of DP fixes, and some backlight fix.
* tag 'drm-intel-fixes-2014-10-30' of git://anongit.freedesktop.org/drm-intel:
drm/i915/dp: only use training pattern 3 on platforms that support it
drm/i915: Ignore VBT backlight check on Macbook 2, 1
drm/i915: Fix GMBUSFREQ on vlv/chv
drm/i915: Ignore long hpds on eDP ports
drm/i915: Do a dummy DPCD read before the actual read