feat(intel): add SMC support for Get USERCODE

This patch adds SMC support for enquiring FPGA's User Code.

Signed-off-by: Abdul Halim, Muhammad Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Signed-off-by: Jit Loon Lim <jit.loon.lim@intel.com>
Signed-off-by: Sieu Mun Tang <sieu.mun.tang@intel.com>
Change-Id: I82c1fa9390b6f7509b2284d51e199fb8b6a9b1ad
diff --git a/plat/intel/soc/common/include/socfpga_mailbox.h b/plat/intel/soc/common/include/socfpga_mailbox.h
index e1c128b..09dd117 100644
--- a/plat/intel/soc/common/include/socfpga_mailbox.h
+++ b/plat/intel/soc/common/include/socfpga_mailbox.h
@@ -42,6 +42,7 @@
 #define MBOX_CMD_CANCEL			0x03
 #define MBOX_CMD_VAB_SRC_CERT		0x0B
 #define MBOX_CMD_GET_IDCODE		0x10
+#define MBOX_CMD_GET_USERCODE		0x13
 #define MBOX_CMD_REBOOT_HPS		0x47
 
 /* Reconfiguration Commands */