Model KeyStore security level in keymaster worker

On certain device configurations the security level reported by the
Keymaster HAL differs from the security level understood in KeyStore.
Namely, on devices with only a software Keymaster, KeyStore will set it
in the TEE slot, and create a new in-process legacy Keymaster for the
software slot.

This change introduces a field to keymaster worker to represent the
security level that KeyStore understands this worker to operate on.

Bug: 167412989
Test: atest CtsKeystoreTestCases
Change-Id: Ifeaa4782913be45d89cdd175a02302c7dc318719
3 files changed