mkimage: Add a missing free() to fit_import_data()

The space allocated to fdt is not freed on error. Fix it.

Reported-by: Coverity (CID: 138494)

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

tools/fit_image.c

@@ -541,6 +541,7 @@ static int fit_import_data(struct image_tool_params *params, const char *fname)
 	ret = 0;
 
 err:
+	free(fdt);
 	close(fd);
 	return ret;
 }