tools: Check arguments in fit_check_sign/fit_info

These tools crash if no arguments are provided. Add checks to avoid this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>
diff --git a/tools/fit_info.c b/tools/fit_info.c
index afbed7b..481ac6d 100644
--- a/tools/fit_info.c
+++ b/tools/fit_info.c
@@ -68,6 +68,18 @@
 			break;
 		}
 
+	if (!fdtfile) {
+		fprintf(stderr, "%s: Missing fdt file\n", *argv);
+		usage(*argv);
+	}
+	if (!nodename) {
+		fprintf(stderr, "%s: Missing node name\n", *argv);
+		usage(*argv);
+	}
+	if (!propertyname) {
+		fprintf(stderr, "%s: Missing property name\n", *argv);
+		usage(*argv);
+	}
 	ffd = mmap_fdt(cmdname, fdtfile, 0, &fit_blob, &fsbuf, false);
 
 	if (ffd < 0) {