Service: Add a new SLIH test

This patch adds a new SLIH test Partition and new IRQ test suite.
The test logic for SLIH - previously IRQ test - is simplified a lot
as well.

This service is intended to replace the tfm_irq_test_1 service.

Change-Id: Ie319bd57121f73125819bcfbb80943cc557533d9
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/test/suites/irq/irq_testsuite.h b/test/suites/irq/irq_testsuite.h
new file mode 100644
index 0000000..934965f
--- /dev/null
+++ b/test/suites/irq/irq_testsuite.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#ifndef __IRQ_TESTSUITE_H__
+#define __IRQ_TESTSUITE_H__
+
+#include "test_framework.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void register_testsuite_irq_test(struct test_suite_t *p_test_suite);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __IRQ_TESTSUITE_H__ */