ALSA: sh: constify snd_pcm_ops structures

snd_pcm_ops are not supposed to change at runtime. All functions
working with snd_pcm_ops provided by <sound/pcm.h> work with
const snd_pcm_ops. So mark the non-const structs as const.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/sh/sh_dac_audio.c b/sound/sh/sh_dac_audio.c
index a077f1c..e71e6a7 100644
--- a/sound/sh/sh_dac_audio.c
+++ b/sound/sh/sh_dac_audio.c
@@ -252,7 +252,7 @@ snd_pcm_uframes_t snd_sh_dac_pcm_pointer(struct snd_pcm_substream *substream)
 }
 
 /* pcm ops */
-static struct snd_pcm_ops snd_sh_dac_pcm_ops = {
+static const struct snd_pcm_ops snd_sh_dac_pcm_ops = {
 	.open		= snd_sh_dac_pcm_open,
 	.close		= snd_sh_dac_pcm_close,
 	.ioctl		= snd_pcm_lib_ioctl,