feat(mt8188): add RTC support

TEST=build pass.
BUG=b:233720142

Signed-off-by: Song Fan <ot_song.fan@mediatek.corp-partner.google.com>
Change-Id: I348eff0f53341593f74a63780e2e8298cbc3ec88
diff --git a/plat/mediatek/drivers/rtc/mt8188/rtc.h b/plat/mediatek/drivers/rtc/mt8188/rtc.h
new file mode 100644
index 0000000..734e89f
--- /dev/null
+++ b/plat/mediatek/drivers/rtc/mt8188/rtc.h
@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2022, MediaTek Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef RTC_H
+#define RTC_H
+
+#include <rtc_mt6359p.h>
+
+#endif  /* RTC_H */