kselftest/arm64: Allow signal tests to trigger from a function

Currently we have the facility to specify custom code to trigger a signal
but none of the tests use it and for some reason the framework requires us
to also specify a signal to send as a trigger in order to make use of a
custom trigger. This doesn't seem to make much sense, instead allow the
use of a custom trigger function without specifying a signal to inject.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211210184133.320748-6-broonie@kernel.orgSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

tools/testing/selftests/arm64/signal/test_signals_utils.c

@@ -310,14 +310,12 @@ int test_setup(struct tdescr *td)
 
 int test_run(struct tdescr *td)
 {
-	if (td->sig_trig) {
-		if (td->trigger)
-			return td->trigger(td);
-		else
-			return default_trigger(td);
-	} else {
+	if (td->trigger)
+		return td->trigger(td);
+	else if (td->sig_trig)
+		return default_trigger(td);
+	else
 		return td->run(td, NULL, NULL);
-	}
 }
 
 void test_result(struct tdescr *td)