drm/nouveau/core: remove NV_D0 family

The one place where it mattered has been replaced with a class check,
which is more appropriate anyway.

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

drivers/gpu/drm/nouveau/nouveau_backlight.c

@@ -231,7 +231,6 @@ nouveau_backlight_init(struct drm_device *dev)
 			return nv40_backlight_init(connector);
 		case NV_50:
 		case NV_C0:
-		case NV_D0:
 		case NV_E0:
 			return nv50_backlight_init(connector);
 		default: