drm/gf100-/gr: add support for zero bandwidth clear

Default ZBC table is compatible with binary driver defaults.

Userspace will need to be updated to take full advantage of this
feature, however, some applications will see a performance boost
without updated drivers.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --cc drivers/gpu/drm/nouveau/core/engine/graph/gk20a.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/graph/gm107.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/graph/nv108.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/graph/nvc0.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/graph/nvc0.h
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/graph/nvc1.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/graph/nvc8.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/graph/nve4.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/graph/nvf0.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/nvif/class.h
Simple merge