refactor the i915 GVT support

[Jason Gunthorpe]

On Tue, Sep 28, 2021 at 02:35:06PM +0000, Wang, Zhi A wrote:

> Yes. I was thinking of the possibility of putting off some work later so 
> that we don't need to make a lot of changes. GVT-g needs to take a 
> snapshot of GPU registers as the initial virtual states for other vGPUs, 
> which requires the initialization happens at a certain early time of 
> initialization of i915. I was thinking maybe we can take other patches 
> from Christoph like "de-virtualize*" except this one because currently 
> we have to maintain a TEST-ONLY patch on our tree to prevent i915 built 
> as kernel module.

How about just capture these registers in the main module/device and
not try so hard to isolate it to the gvt stuff?

Jason