Add SeqNum as an the external_aad in CryptoPayload am: 73f66600e9

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2876314

Change-Id: I81fd4bae4310011c76513867cc832a3938ea25e9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>