fix(plat/zynqmp): fix coverity scan warnings

- Fix uninitialized variable use
- Fix array overrun issue

Signed-off-by: Tanmay Shah <tanmay.shah@xilinx.com>
Signed-off-by: Ronak Jain <ronak.jain@xilinx.com>
Change-Id: I604416531122c9208793d66c26b1fa69c95f3165
diff --git a/plat/xilinx/zynqmp/pm_service/pm_client.c b/plat/xilinx/zynqmp/pm_service/pm_client.c
index 1f54430..3cd48a7 100644
--- a/plat/xilinx/zynqmp/pm_service/pm_client.c
+++ b/plat/xilinx/zynqmp/pm_service/pm_client.c
@@ -217,10 +217,11 @@
 			node = irq_to_pm_node(irq);
 			reg &= ~lowest_set;
 
-			if ((node != NODE_UNKNOWN) &&
-			    (!pm_wakeup_nodes_set[node])) {
-				ret = pm_set_wakeup_source(NODE_APU, node, 1);
-				pm_wakeup_nodes_set[node] = !ret;
+			if (node > NODE_UNKNOWN && node < NODE_MAX) {
+				if (pm_wakeup_nodes_set[node] == 0U) {
+					ret = pm_set_wakeup_source(NODE_APU, node, 1U);
+					pm_wakeup_nodes_set[node] = (ret == PM_RET_SUCCESS) ? 1U : 0U;
+				}
 			}
 		}
 	}