drm/nouveau: finalise nvkm namespace switch (no binary change)

The namespace of NVKM is being changed to nvkm_ instead of nouveau_,
which will be used for the DRM part of the driver.  This is being
done in order to make it very clear as to what part of the driver a
given symbol belongs to, and as a minor step towards splitting the
DRM driver out to be able to stand on its own (for virt).

Because there's already a large amount of churn here anyway, this is
as good a time as any to also switch to NVIDIA's device and chipset
naming to ease collaboration with them.

A comparison of objdump disassemblies proves no code changes.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nouveau_platform.c b/drivers/gpu/drm/nouveau/nouveau_platform.c
index 5e6a2c9..dc5900b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_platform.c
+++ b/drivers/gpu/drm/nouveau/nouveau_platform.c
@@ -152,7 +152,7 @@
 {
 	struct drm_device *drm_dev = platform_get_drvdata(pdev);
 	struct nouveau_drm *drm = nouveau_drm(drm_dev);
-	struct nouveau_device *device = nvxx_device(&drm->device);
+	struct nvkm_device *device = nvxx_device(&drm->device);
 	struct nouveau_platform_gpu *gpu = nv_device_to_platform(device)->gpu;
 
 	nouveau_drm_device_remove(drm_dev);