feat(psa): interface with RSS for retrieving ROTPK

Adding the AP/RSS interface for reading the ROTPK.

The read interface implements the psa_call:
psa_call(RSS_CRYPTO_HANDLE, PSA_IPC_CALL,
         in_vec, IOVEC_LEN(in_vec),
         out_vec,  IOVEC_LEN(out_vec));

where the in_vec indicates which of the 3 ROTPKs we want,
and the out_vec stores the ROTPK value we get back from RSS.

Through this service, we will be able to read any of the 3
ROTPKs used on a CCA platform:
- ROTPK for CCA firmware (BL2, BL31, RMM).
- ROTPK for secure firmware.
- ROTPK for non-secure firmware.

Change-Id: I44c615588235cc797fdf38870b74b4c422be0a72
Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
4 files changed