Introduce proper memory management for SANs

DirectoryName parsing performs allocation that has to be handled.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/tests/suites/test_suite_x509parse.function b/tests/suites/test_suite_x509parse.function
index abdc5aa..29c0574 100644
--- a/tests/suites/test_suite_x509parse.function
+++ b/tests/suites/test_suite_x509parse.function
@@ -461,7 +461,9 @@
              * If san type not supported, ignore.
              */
             if (ret == 0) {
-                TEST_ASSERT(verify_parse_san(&san, &p, &n) == 0);
+                ret = verify_parse_san(&san, &p, &n);
+                mbedtls_x509_free_subject_alt_name(&san);
+                TEST_EQUAL(ret, 0);
             }
             cur = cur->next;
         }