tools: Add an error code when fit_handle_file() fails

The error code may provide useful information for debugging. Add it to the
error string.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Teddy Reed <teddy.reed@gmail.com>

tools/fit_image.c

@@ -651,8 +651,8 @@ static int fit_handle_file(struct image_tool_params *params)
 	}
 
 	if (ret) {
-		fprintf(stderr, "%s Can't add hashes to FIT blob\n",
-			params->cmdname);
+		fprintf(stderr, "%s Can't add hashes to FIT blob: %d\n",
+			params->cmdname, ret);
 		goto err_system;
 	}