Enhance fit_check_sign to check all images

At present this tool only checks the configuration signing. Have it also
look at each of the images in the configuration and confirm that they
verify.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de> (v1)
diff --git a/tools/fit_check_sign.c b/tools/fit_check_sign.c
index 768be2f..69e99c0 100644
--- a/tools/fit_check_sign.c
+++ b/tools/fit_check_sign.c
@@ -80,10 +80,13 @@
 
 	image_set_host_blob(key_blob);
 	ret = fit_check_sign(fit_blob, key_blob);
-	if (!ret)
+	if (!ret) {
 		ret = EXIT_SUCCESS;
-	else
+		fprintf(stderr, "Signature check OK\n");
+	} else {
 		ret = EXIT_FAILURE;
+		fprintf(stderr, "Signature check Bad (error %d)\n", ret);
+	}
 
 	(void) munmap((void *)fit_blob, fsbuf.st_size);
 	(void) munmap((void *)key_blob, ksbuf.st_size);