fix(nxp-tools): fix coverity issue

Check the value is not NULL.

Signed-off-by: Jiafei Pan <Jiafei.Pan@nxp.com>
Change-Id: If753e9875153a8e31498addf89202c953abf64ef
diff --git a/tools/nxp/create_pbl/create_pbl.c b/tools/nxp/create_pbl/create_pbl.c
index 9457a00..792747f 100644
--- a/tools/nxp/create_pbl/create_pbl.c
+++ b/tools/nxp/create_pbl/create_pbl.c
@@ -823,7 +823,9 @@
 		}
 	}
 
-	if ((args & MAND_ARG_MASK) != MAND_ARG_MASK) {
+	if ((args & MAND_ARG_MASK) != MAND_ARG_MASK
+			|| pblimg.rcw_nm == NULL
+			|| pblimg.imagefile == NULL) {
 		print_usage();
 	}