Add the GENERATE_TIMESTAMP_TOKEN type to the message enum am: 3a6235a8ff am: e238e0f421 am: 741b0b1c78

Original change: https://android-review.googlesource.com/c/platform/system/keymaster/+/1640611

Change-Id: I762b9fcd6910482745a0972522e29291e07af440