plat/arm/sgi: add platform id value for rdn2 platform

In preparation for adding the board support for RD-N2 platform, add
macros to define the platform id and the corresponding SCMI platform
info for the RD-N2 platform.

Change-Id: Ie764ae618732b39e316f7ed080421f5d79adab21
Signed-off-by: Aditya Angadi <aditya.angadi@arm.com>
diff --git a/plat/arm/css/sgi/include/sgi_variant.h b/plat/arm/css/sgi/include/sgi_variant.h
index f4c5300..eb12f3f 100644
--- a/plat/arm/css/sgi/include/sgi_variant.h
+++ b/plat/arm/css/sgi/include/sgi_variant.h
@@ -17,6 +17,9 @@
 /* SID Version values for RD-Daniel */
 #define RD_DANIEL_SID_VER_PART_NUM		0x078a
 
+/* SID Version values for RD-N2 */
+#define RD_N2_SID_VER_PART_NUM			0x07B7
+
 /* Structure containing SGI platform variant information */
 typedef struct sgi_platform_info {
 	unsigned int platform_id;	/* Part Number of the platform */