ASoC: msm8916-wcd-digital: convert license header to SPDX

Convert the GPLv2-only license header to SPDX.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/msm8916-wcd-digital.c

-/* Copyright (c) 2016, The Linux Foundation. All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 and
- * only version 2 as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- */
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2016, The Linux Foundation. All rights reserved.
 
 #include <linux/module.h>
 #include <linux/err.h>