Attest: Support kid parameter in COSE_Mac0 structure header

Add a HAL API tfm_plat_get_symmetric_iak_id() to fetch kid from
platform.
Implement an example of this HAL API.

Add attest_get_symmetric_iak_id() to pass the kid value to token
generation of symmetric key algorithm based Initial Attestation.

Change-Id: I642f7a03f1738c8fe77f11fc2ae91652fc01df29
Signed-off-by: David Hu <david.hu@arm.com>
6 files changed