mt8173: Reorganize plat SiP functions

Due to the changes in Mediatek platform common code, we need to move
plat related SiP functions to plat folder.

Change-Id: I6b14b988235205a5858b4bf49043bc79d0512b06
diff --git a/plat/mediatek/common/mtk_sip_svc.c b/plat/mediatek/common/mtk_sip_svc.c
index 6591659..021511e 100644
--- a/plat/mediatek/common/mtk_sip_svc.c
+++ b/plat/mediatek/common/mtk_sip_svc.c
@@ -33,6 +33,7 @@
 #include <mmio.h>
 #include <mtk_plat_common.h>
 #include <mtk_sip_svc.h>
+#include <plat_sip_calls.h>
 #include <runtime_svc.h>
 #include <uuid.h>
 
@@ -117,7 +118,8 @@
 	switch (smc_fid) {
 	case SIP_SVC_CALL_COUNT:
 		/* Return the number of Mediatek SiP Service Calls. */
-		SMC_RET1(handle, MTK_SIP_NUM_CALLS);
+		SMC_RET1(handle,
+			 MTK_COMMON_SIP_NUM_CALLS + MTK_PLAT_SIP_NUM_CALLS);
 
 	case SIP_SVC_UID:
 		/* Return UID to the caller */