drm/nouveau: do not leak in nv20_graph_create

If we return due to an unknown chipset in
drivers/gpu/drm/nouveau/nv20_graph.c:nv20_graph_create() we'll leak the
memory allocated to 'pgraph'.

This patch should fix the leak.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Reviewed-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nv20_graph.c

@@ -753,6 +753,7 @@ nv20_graph_create(struct drm_device *dev)
 			break;
 		default:
 			NV_ERROR(dev, "PGRAPH: unknown chipset\n");
+			kfree(pgraph);
 			return 0;
 		}
 	} else {
@@ -774,6 +775,7 @@ nv20_graph_create(struct drm_device *dev)
 			break;
 		default:
 			NV_ERROR(dev, "PGRAPH: unknown chipset\n");
+			kfree(pgraph);
 			return 0;
 		}
 	}