feat(mediatek): add smcc call for MSDC

Some registers of MSDC need to be set in ATF, so we add MSDC drivers.

Change-Id: Idde51a136ad08dbaece0bdaa804b934fca7046b6
diff --git a/plat/mediatek/mt8186/include/plat_sip_calls.h b/plat/mediatek/mt8186/include/plat_sip_calls.h
index 2b99fdb..f5c15e3 100644
--- a/plat/mediatek/mt8186/include/plat_sip_calls.h
+++ b/plat/mediatek/mt8186/include/plat_sip_calls.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, MediaTek Inc. All rights reserved.
+ * Copyright (c) 2021-2022, MediaTek Inc. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -10,6 +10,6 @@
 /*******************************************************************************
  * Plat SiP function constants
  ******************************************************************************/
-#define MTK_PLAT_SIP_NUM_CALLS		(4)
+#define MTK_PLAT_SIP_NUM_CALLS		(6)
 
 #endif /* PLAT_SIP_CALLS_H */