misc i915 fixes.
* tag 'drm-intel-fixes-2016-02-04' of git://anongit.freedesktop.org/drm-intel:
drm/i915: refine qemu south bridge detection
drm/i915: Remove select to deleted STOP_MACHINE from Kconfig
drm/i915: Fix NULL plane->fb oops on SKL
drm/i915: Don't reject primary plane windowing with color keying enabled on SKL+
drm/i915/dp: fall back to 18 bpp when sink capability is unknown
drm/i915: Make sure DC writes are coherent on flush.
87d0f93961