Split multipart AEAD contexts into two parts

Split to data required for internal implementation and data required for
driver implementation with data left over for the PSA layer.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/include/psa/crypto_driver_contexts_primitives.h b/include/psa/crypto_driver_contexts_primitives.h
index 104d4bd..4fba9eb 100644
--- a/include/psa/crypto_driver_contexts_primitives.h
+++ b/include/psa/crypto_driver_contexts_primitives.h
@@ -65,5 +65,13 @@
 #endif
 } psa_driver_cipher_context_t;
 
+typedef union {
+    unsigned dummy; /* Make sure this union is always non-empty */
+    mbedtls_psa_aead_operation_t mbedtls_ctx;
+#if defined(PSA_CRYPTO_DRIVER_TEST)
+    mbedtls_transparent_test_driver_aead_operation_t transparent_test_driver_ctx;
+#endif
+} psa_driver_aead_context_t;
+
 #endif /* PSA_CRYPTO_DRIVER_CONTEXTS_PRIMITIVES_H */
 /* End of automatically generated file. */