Configure the RNG in 3.6 testcase

In Mbed TLS 3.6 we still need to manually configure the RNG for TLS. Add
this to the testcase for default verify_result.

Signed-off-by: David Horstmann <david.horstmann@arm.com>

tests/suites/test_suite_ssl.function

@@ -6019,6 +6019,7 @@ void verify_result_without_handshake(void)
 
     mbedtls_ssl_conf_authmode(&conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
     mbedtls_ssl_conf_ca_chain(&conf, NULL, NULL);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
 
     TEST_EQUAL(mbedtls_ssl_setup(&ssl, &conf), 0);