hwdec/d3d11va: fix a possible memory leak

video/out/d3d11/hwdec_d3d11va.c

@@ -67,6 +67,7 @@ static void uninit(struct ra_hwdec *hw)
 {
     struct priv_owner *p = hw->priv;
     hwdec_devices_remove(hw->devs, &p->hwctx);
+    av_buffer_unref(&p->hwctx.av_device_ref);
     SAFE_RELEASE(p->device);
     SAFE_RELEASE(p->device1);
 }