- skl wm fixes (Lyude, Matt, Maarten)

- cleanup of kdev/drm_dev/i915_dev handling (David Weinehall)
- make (most) encoders take advantage of atomic states (Maarten)
- MMAP_GTT_VERSION driver param to announce that gtt mmaps are reliable (Chris)
- allow contexts on all rings (Chris)
- a few fixes (around diagnostic messages) to make BAT less noisy
- misc fixes and cleanups all over, as usual