drm/gf100-/gr: unhardcode attribute cb config

drivers/gpu/drm/nouveau/core/engine/graph/ctxgk110b.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxgk20a.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxgm107.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxnv108.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxnvc0.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxnvc0.h

drivers/gpu/drm/nouveau/core/engine/graph/ctxnvc1.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxnvc4.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxnvc8.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxnvd7.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxnvd9.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxnve4.c

drivers/gpu/drm/nouveau/core/engine/graph/ctxnvf0.c