drm/nouveau/nouveau: fix memory leak in nouveau_crtc_page_flip()

Fix a memory leak in the nouveau_crtc_page_flip() error handling path.
Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_display.c

@@ -610,7 +610,7 @@ nouveau_crtc_page_flip(struct drm_crtc *crtc, struct drm_framebuffer *fb,
 	ret = nouveau_fence_sync(fence, chan);
 	nouveau_fence_unref(&fence);
 	if (ret)
-		return ret;
+		goto fail_free;
 
 	if (new_bo != old_bo) {
 		ret = nouveau_bo_pin(new_bo, TTM_PL_FLAG_VRAM);