Attest: Use macros generated by tools

- Use the SID and service version defined in sid.h.
- Use signal defined in tfm_initial_attestation.h.
- Remove tfm_attest_defs.h and tfm_attest_signal.h.

Change-Id: I36a5be19c8d89ca1e9dfb5978438bb0e66f3cde7
Signed-off-by: Edison Ai <edison.ai@arm.com>