ASoC: switch audio drivers to SPDX identifier

Switch audio drivers to SPDX identifier on msm-4.19.

Change-Id: Ic3f0230a516db251b8d81e8a7e73dbc04d66fe1b
Signed-off-by: Meng Wang <mengw@codeaurora.org>

dsp/q6_init.h

@@ -1,15 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
-Copyright (c) 2017, 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.
-*
+ * Copyright (c) 2017, The Linux Foundation. All rights reserved.
 */
 
 #ifndef __Q6_INIT_H__