Tests: add missing group termination

Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index e114cae..b4a615c 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -5604,7 +5604,8 @@
 #if defined(MBEDTLS_TIMING_C)
     mbedtls_timing_delay_context timer_client, timer_server;
 #endif
-    uint16_t iana_tls_group_list[] = { MBEDTLS_SSL_IANA_TLS_GROUP_SECP256R1 };
+    uint16_t iana_tls_group_list[] = { MBEDTLS_SSL_IANA_TLS_GROUP_SECP256R1,
+                                       MBEDTLS_SSL_IANA_TLS_GROUP_NONE };
 
     mbedtls_test_message_queue server_queue, client_queue;
     mbedtls_test_message_socket_context server_context, client_context;