Add internal struct for iop export public-key context

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/tf-psa-crypto/include/psa/crypto_builtin_composites.h b/tf-psa-crypto/include/psa/crypto_builtin_composites.h
index 14e759b..c6bd0fd 100644
--- a/tf-psa-crypto/include/psa/crypto_builtin_composites.h
+++ b/tf-psa-crypto/include/psa/crypto_builtin_composites.h
@@ -248,4 +248,22 @@
 #define MBEDTLS_PSA_KEY_AGREEMENT_IOP_INIT { 0 }
 #endif
 
+/* Context structure for the Mbed TLS interruptible export public-key implementation. */
+typedef struct {
+#if defined(MBEDTLS_ECP_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+    mbedtls_ecp_keypair *MBEDTLS_PRIVATE(key);
+    mbedtls_ecp_restart_ctx MBEDTLS_PRIVATE(restart_ctx);
+    uint32_t MBEDTLS_PRIVATE(num_ops);
+#else
+    /* Make the struct non-empty if algs not supported. */
+    unsigned MBEDTLS_PRIVATE(dummy);
+#endif
+} mbedtls_psa_export_public_key_iop_operation_t;
+
+#if defined(MBEDTLS_ECP_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+#define MBEDTLS_PSA_EXPORT_PUBLIC_KEY_IOP_INIT { 0, MBEDTLS_ECP_RESTART_INIT, 0 }
+#else
+#define MBEDTLS_PSA_EXPORT_PUBLIC_KEY_IOP_INIT { 0 }
+#endif
+
 #endif /* PSA_CRYPTO_BUILTIN_COMPOSITES_H */