freedreno: Common device info datastructure

We've accumulated a number of per-gen or even per-device parameters for things like alignments, sizes, etc., and with turnip these now have to be duplicated in two separate drivers. With private memory there are going to be even more parameters to fill out, and rather than adding yet more duplicated code I thought I'd clean this up. I'm splitting this up from the main private memory MR because it's a fairly self-contained refactor that's ready to land now.