AuthGraph: drop now-unused StdClock am: 20c6549f34 am: 4ea954c721

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

Change-Id: I109a4a2847748ba021c215bca6b529c5cf7d186b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>