ASoC: soc-dpcm.h: convert to SPDX identifiers

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc-dpcm.h

-/*
+/* SPDX-License-Identifier: GPL-2.0
+ *
  * linux/sound/soc-dpcm.h -- ALSA SoC Dynamic PCM Support
  *
  * Author:		Liam Girdwood <lrg@ti.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #ifndef __LINUX_SND_SOC_DPCM_H