Brief description of changes:
- Enable Qemu kernel configs for Trusted Keys.
- Add keyutils buildroot package.
- Enable Trusted Keys early TA in OP-TEE.
- Create a new test script (trusted-keys.exp) which is invoked as part
  of "make check" for automated Trusted Keys tests.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
Acked-by: Jerome Forissier <jerome@forissier.org>