[linux-morello] Linux DRM purecap "RFC"

Just thought it's time to share the current state of drm purecap work:

Kernel: https://git.morello-project.org/carhai01/linux-drm-purecap/-/commit/7ea169ab...

DRM: https://git.morello-project.org/carhai01/drm-linux-morello-purecap/-/commit/...

All the DRM tests ow pass for compat and purecap.

I'm of 2 minds in the kernel code. I could go mimic the "copy field" stuff from EBPF but it's still going to be a bit messy. DRM code calls everything "compat" "32" so I'm keeping with that naming scheme (compat for us is 64bit). I've kept the compat structs at the entry points. I could copy to a local "native" struct I guess... It'd mean I carry more local data than I actually need/use.

Anyway... comments?