drm/nouveau/ttm: prevent double-free in nouveau_sgdma_create_ttm() failure path

TTM calls the destructor on its own already...
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_sgdma.c

@@ -104,9 +104,7 @@ nouveau_sgdma_create_ttm(struct ttm_bo_device *bdev,
 	else
 		nvbe->ttm.ttm.func = &nv50_sgdma_backend;
 
-	if (ttm_dma_tt_init(&nvbe->ttm, bdev, size, page_flags, dummy_read_page)) {
-		kfree(nvbe);
+	if (ttm_dma_tt_init(&nvbe->ttm, bdev, size, page_flags, dummy_read_page))
 		return NULL;
-	}
 	return &nvbe->ttm.ttm;
 }