intel: Create SiP service header file

Separate SiP related definition from mailbox header file

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I45ba540f29d9261007f7ec23469358747cf140b4
diff --git a/plat/intel/soc/common/socfpga_sip_svc.c b/plat/intel/soc/common/socfpga_sip_svc.c
index 88750d7..61218eb 100644
--- a/plat/intel/soc/common/socfpga_sip_svc.c
+++ b/plat/intel/soc/common/socfpga_sip_svc.c
@@ -10,6 +10,7 @@
 #include <tools_share/uuid.h>
 
 #include "socfpga_mailbox.h"
+#include "socfpga_sip_svc.h"
 
 /* Number of SiP Calls implemented */
 #define SIP_NUM_CALLS		0x3