amdfwtool: Add missing license header

Change-Id: Id466e733d421602cfe0403ead95e417f0bb37eb4
Signed-off-by: Zheng Bao <fishbaozi@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55159
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>

util/amdfwtool/data_parse.c

@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
 #include <stdio.h>
 #include <regex.h>
 #include <string.h>