fix(xilinx): typecast operands to match data type

This corrects the MISRA violation C2012-10.1:
Operands shall not be of an inappropriate essential type.
The condition is explicitly checked against 0U, appending 'U' and
typecasting for unsigned comparison.

Change-Id: I675f1b2ac408b70a9ca307fb5161ebb8e597897c
Signed-off-by: Nithin G <nithing@amd.com>
Signed-off-by: Maheedhar Bollapalli <maheedharsai.bollapalli@amd.com>
diff --git a/plat/xilinx/common/plat_startup.c b/plat/xilinx/common/plat_startup.c
index c58b799..c5e3732 100644
--- a/plat/xilinx/common/plat_startup.c
+++ b/plat/xilinx/common/plat_startup.c
@@ -175,7 +175,7 @@
 {
 	const struct xbl_handoff_params *HandoffParams;
 
-	if (!handoff_addr) {
+	if (handoff_addr == 0U) {
 		WARN("BL31: No handoff structure passed\n");
 		return XBL_HANDOFF_NO_STRUCT;
 	}