mbedtls_ssl_handshake_free: take the SSL context as argument

Change the signature of mbedtls_ssl_handshake_free again. Now take the
whole SSL context as argument and not just the configuration and the
handshake substructure.

This is in preparation for changing the asynchronous cancel callback
to take the SSL context as an argument.
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 4c7205d..334b5d8 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -414,11 +414,9 @@
  * \brief           Free referenced items in an SSL handshake context and clear
  *                  memory
  *
- * \param conf      SSL configuration
- * \param handshake SSL handshake context
+ * \param ssl       SSL context
  */
-void mbedtls_ssl_handshake_free( const mbedtls_ssl_config *conf,
-                                 mbedtls_ssl_handshake_params *handshake );
+void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl );
 
 int mbedtls_ssl_handshake_client_step( mbedtls_ssl_context *ssl );
 int mbedtls_ssl_handshake_server_step( mbedtls_ssl_context *ssl );