test: remove an unnecssary arg for the iotest

That's what copy/pasting does... this argument is the user_data pointer which
we don't care about here.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

test/iotest.c

@@ -167,5 +167,5 @@ static const MunitSuite iotest_suite = {
 int
 main(int argc, char* argv[MUNIT_ARRAY_PARAM(argc + 1)])
 {
-  return munit_suite_main(&iotest_suite, (void*) "io/", argc, argv);
+	return munit_suite_main(&iotest_suite, NULL, argc, argv);
 }