drm/nouveau: Do not leak client objects

The memory allocated for a nouveau_cli object in nouveau_cli_create() is
never freed. Free the memory in nouveau_cli_destroy() to plug this leak.

kmemleak recorded this after running a couple of nouveau test programs.
Note that kmemleak points at drm_open_helper() because for some reason
it thinks that skipping the first two stack frames is a good idea.
Signed-off-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_drm.c

@@ -128,6 +128,7 @@ nouveau_cli_destroy(struct nouveau_cli *cli)
 	nvkm_vm_ref(NULL, &nvxx_client(&cli->base)->vm, NULL);
 	nvif_client_fini(&cli->base);
 	usif_client_fini(cli);
+	kfree(cli);
 }
 
 static void