[Intel-gfx] intel display struct refactor

[Dave Airlie]

I posted an intro set of patches to intel-gfx earlier, but I got a bit
OCD and kept going here.

https://cgit.freedesktop.org/~airlied/linux/log/?h=i915-display-struct-refactor

Mainly looking to see if this is interesting enough refactor to get it
landed, I realise it would be quite disruptive. I'd also like to see
if I missed anything really obvious, I wasn't sure whether
vbt/opregion were suitable and I may have left some stuff behind.

Dave.