stdcalltest: Add secure timer am: 963318fdc2

Original change: https://android-review.googlesource.com/c/trusty/lk/trusty/+/3439566

Change-Id: Ib1efd3601c0441174ba03a2ffffa7aff8e22613c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>