ASoC: mxs: Add missing MODULE_LICENSE("GPL")

The sound driver refuses to load as module, because of the missing
MODULE_LICENSE("GPL").
The file header indicates that the driver is indeed published under
the GPL.

Signed-off-by: Lothar Waßmann <[email protected]>
Acked-by: Wolfram Sang <[email protected]>
Signed-off-by: Mark Brown <[email protected]>

Author: lw-karo

sound/soc/mxs/mxs-pcm.c

@@ -357,3 +357,5 @@ static void __exit snd_mxs_pcm_exit(void)
 	platform_driver_unregister(&mxs_pcm_driver);
 }
 module_exit(snd_mxs_pcm_exit);
+
+MODULE_LICENSE("GPL");