drm-next + i915 CVE yolo merge

[Dave Airlie]

The landing of the i915 CVE fixes into Linus tree has created a bit of
a mess in linux-next and downstream in drm-next trees.

I talked to Daniel and he had talked to Joonas a bit, and I decided to
go with what Daniel describes as the YOLO merge, where I just solve it
and pray, and everyone else verifies/fixes it.

In my favour I've been reading these patches for a couple of months
now and applied them to a lot of places, so I'm quite familiar with
what they are doing.

The worst culprit was the RC6 ctx corruption fix since the whole of
rc6 got refactored in next. However I also had access to a version of
this patch Jon wrote on drm-tip a couple of weeks ago.

I took that patch, applied it and fixed it up on top of drm-next. Then
I backmerged the commit that also went into Linus' tree. Then I
removed any evidence of the RC6 patch from Linus' tree and left the
newer version pieces in place. The other stuff mostly merged fine and
the results looked fine, but I'd definitely think everyone at Intel
should be staring at it, and my dinq tip resolutions ASAP and
hopefully it goes into CI and comes out smelling of something good.

Let me know if it's all horrible asap,
Thanks,
Dave.