GIC: Add API to raise secure SGI

API documentation updated.

Change-Id: I129725059299af6cc612bafa8d74817f779d7c4f
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/include/lib/aarch64/arch.h b/include/lib/aarch64/arch.h
index 3fb6846..bbe1e4f 100644
--- a/include/lib/aarch64/arch.h
+++ b/include/lib/aarch64/arch.h
@@ -77,6 +77,7 @@
 #define ICC_IAR1_EL1    S3_0_c12_c12_0
 #define ICC_EOIR0_EL1   S3_0_c12_c8_1
 #define ICC_EOIR1_EL1   S3_0_c12_c12_1
+#define ICC_SGI0R_EL1	S3_0_c12_c11_7
 
 /*******************************************************************************
  * Generic timer memory mapped registers & offsets