feat(mediatek): add APU init flow

The patch brings preparation steps before powering on APU
(AI processing unit)

Change-Id: Ica01e035153ec6f3af0de6ba2c66b17a064f8c89
diff --git a/plat/mediatek/drivers/apusys/apusys.c b/plat/mediatek/drivers/apusys/apusys.c
new file mode 100644
index 0000000..1d34627
--- /dev/null
+++ b/plat/mediatek/drivers/apusys/apusys.c
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2023, MediaTek Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/* TF-A system header */
+#include <common/debug.h>
+
+/* Vendor header */
+#include "apusys.h"
+#include "apusys_power.h"
+#include <lib/mtk_init/mtk_init.h>
+
+int apusys_init(void)
+{
+	apusys_power_init();
+	return 0;
+}
+MTK_PLAT_SETUP_1_INIT(apusys_init);