mediatek: mt8195: Add SiP service

Add the basic SiP service

Change-Id: I21fe9d85eac4be9101b12c4b6c28294c5b93cb5f
diff --git a/plat/mediatek/mt8195/plat_sip_calls.c b/plat/mediatek/mt8195/plat_sip_calls.c
new file mode 100644
index 0000000..a1e3c36
--- /dev/null
+++ b/plat/mediatek/mt8195/plat_sip_calls.c
@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2020, MediaTek Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <common/debug.h>
+#include <common/runtime_svc.h>
+
+uintptr_t mediatek_plat_sip_handler(uint32_t smc_fid,
+				u_register_t x1,
+				u_register_t x2,
+				u_register_t x3,
+				u_register_t x4,
+				void *cookie,
+				void *handle,
+				u_register_t flags)
+{
+	switch (smc_fid) {
+	default:
+		ERROR("%s: unhandled SMC (0x%x)\n", __func__, smc_fid);
+		break;
+	}
+
+	SMC_RET1(handle, SMC_UNK);
+}