AuthGraph: drop now-unused StdClock am: 20c6549f34 am: d761cc1099 am: b191f99452

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2845875

Change-Id: Id01d7c44b3194f4704d51753a0e43e08b8a9645f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>