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

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

Change-Id: I15b7da658d6144fc0d547c9945828bdefeb0a870
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>