Test: Refine attestation test service

- Move IAK read operation from service init step into specific client
  call handling. OTP read may fail on some develop boards at earlier
  init stage.
- Split the secure and non-secure interface APIs.

Signed-off-by: David Hu <david.hu@arm.com>
Change-Id: I8be534398b5e79dda725f0c0f62296466133c9e7
4 files changed