Add missing dependencies on !MBEDTLS_X509_REMOVE_INFO

Signed-off-by: Chris Jones <christopher.jones@arm.com>
diff --git a/tests/suites/test_suite_x509parse.function b/tests/suites/test_suite_x509parse.function
index 8289cd2..82f7da5 100644
--- a/tests/suites/test_suite_x509parse.function
+++ b/tests/suites/test_suite_x509parse.function
@@ -844,6 +844,8 @@
 
         TEST_ASSERT( strcmp( (char *) output, result_str ) == 0 );
     }
+#else
+    ((void) result_str);
 #endif
 
     mbedtls_x509_crt_free( &crt );