drm/nouveau/mmu: define user interfaces to mmu

drivers/gpu/drm/nouveau/include/nvif/class.h

drivers/gpu/drm/nouveau/include/nvif/if0008.h

drivers/gpu/drm/nouveau/include/nvif/mmu.h

drivers/gpu/drm/nouveau/include/nvkm/subdev/mmu.h

drivers/gpu/drm/nouveau/nvif/Kbuild

drivers/gpu/drm/nouveau/nvif/mmu.c

drivers/gpu/drm/nouveau/nvkm/engine/device/user.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/Kbuild

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/base.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/g84.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/gf100.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/gk104.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/gk20a.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/gm200.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/gm20b.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/gp100.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/gp10b.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/nv04.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/nv41.c

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/nv44.c