drm/nouveau/bus: make external class definitions pointers

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

diff --cc drivers/gpu/drm/nouveau/core/engine/device/nv04.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/device/nv10.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/device/nv20.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/device/nv30.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/device/nv40.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/device/nv50.c
Simple merge

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

diff --cc drivers/gpu/drm/nouveau/core/engine/device/nve0.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/include/subdev/bus.h
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/bus/nv04.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/bus/nv04.h
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/bus/nv31.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/bus/nv50.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/bus/nvc0.c
Simple merge