Adjust logic around log pattern

This is more flexible: the test data gets to decide whether we want to
assert the presence of a pattern or not.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index df9d9bc..20e0995 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -5102,9 +5102,7 @@
         ret = mbedtls_ssl_handshake_step(&server.ssl);
     } while (ret == 0 && server.ssl.state == state);
     TEST_EQUAL(ret,  expected_ret);
-    /* If we're expected to suceeed and we do, that's enough.
-     * If we're expected to fail, also check it was in the expected way. */
-    if (expected_ret != 0) {
+    if (strlen(log_pattern) != 0) {
         TEST_EQUAL(srv_pattern.counter, 1);
     }