Attest: Implement API to get attestation public key

Implement non-secure interface function for IPC and library models and
secure interface function to get the public part of the attestation
key pair.
Add public key getter secure function / service to Initial Attestation
partition manifest.

Change-Id: Idae5f5d5d645afa6d3c7e62e9169387e57932137
Signed-off-by: David Vincze <david.vincze@arm.com>
diff --git a/interface/include/tfm_veneers.h b/interface/include/tfm_veneers.h
index b0b4867..0bcef49 100644
--- a/interface/include/tfm_veneers.h
+++ b/interface/include/tfm_veneers.h
@@ -94,6 +94,7 @@
 /******** TFM_SP_INITIAL_ATTESTATION ********/
 psa_status_t tfm_initial_attest_get_token_veneer(psa_invec *in_vec, size_t in_len, psa_outvec *out_vec, size_t out_len);
 psa_status_t tfm_initial_attest_get_token_size_veneer(psa_invec *in_vec, size_t in_len, psa_outvec *out_vec, size_t out_len);
+psa_status_t tfm_initial_attest_get_public_key_veneer(psa_invec *in_vec, size_t in_len, psa_outvec *out_vec, size_t out_len);
 
 #ifdef TFM_PARTITION_TEST_CORE
 /******** TFM_SP_CORE_TEST ********/