Change over to psa_raw_key_agreement

psa_key_agreement exists, but only in the PSA spec, we have not
implemented it, so refer to the one we actually implemented.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/tf-psa-crypto/include/psa/crypto.h b/tf-psa-crypto/include/psa/crypto.h
index f90ea4c..17a39c3 100644
--- a/tf-psa-crypto/include/psa/crypto.h
+++ b/tf-psa-crypto/include/psa/crypto.h
@@ -4889,7 +4889,7 @@
  *
  * \note                        This function combined with \c
  *                              psa_key_agreement_iop_complete() is equivalent
- *                              to \c psa_key_agreement() but \c
+ *                              to \c psa_raw_key_agreement() but \c
  *                              psa_key_agreement_iop_complete() can return
  *                              early and resume according to the limit set with
  *                              \c psa_interruptible_set_max_ops() to reduce the
@@ -5047,7 +5047,7 @@
  *
  * \note                        This function combined with \c
  *                              psa_key_agreement_iop_setup() is equivalent to
- *                              \c psa_key_agreement() but this
+ *                              \c psa_raw_key_agreement() but this
  *                              function can return early and resume according
  *                              to the limit set with \c
  *                              psa_interruptible_set_max_ops() to reduce the