Update KeymasterEnforcement.

This brings KeymasterEnforcement up to date and cleans it up, making the
code more consistent with the rest of keymaster.  It also makes it
possible to use from Trusty, by virtualizing some time-related functions
that don't work the same in Trusty-land.

Bug: 19511945
Change-Id: I1141c953f227f3ef8a78751d9f04bf4e4922d1f5
8 files changed