Add keystore add_auth

This is for the new addAuthToken keystore method from
I7f7647d9a36ea453ec6d62fc84087ca8f76e53dd. These tokens will be used to
authorize keymaster operations. The tokens are HMAC'd and so shouldn't
be fakeable but this is still limited to system_server only.

Change-Id: I3ff46b676ecac8a878d3aa0a25ba9a8b0c5e1f47
2 files changed