Merge remote-tracking branch 'airlied/drm-next' into drm-intel-next-queued

Pull in Dave's drm-next pull request to have a clean base for 4.6.
Also, we need the various atomic state extensions Maarten recently
created.

Conflicts are just adjacent changes that all resolve to nothing in git
diff.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>