supplicant(vts): Stop adding empty instance for vendor HAL am: b9ddf021d3 am: 8a4e68b788 am: 329fe1ca18

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/1438028

Change-Id: Ib32992f893ff0fc118bf11d0173e5a403b6f8a97