drm/nouveau/gr/nv3x: add 0x0597 kelvin 3d class support

Tested on a NV34. There are reports of this also working on the other
nv3x chips. Largely useful for testing software written for NV2x without
having the actual hardware available.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>