ALSA: ad1816a: 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>

sound/isa/ad1816a/ad1816a_lib.c

@@ -653,7 +653,7 @@ int snd_ad1816a_create(struct snd_card *card,
 	return 0;
 }
 
-static struct snd_pcm_ops snd_ad1816a_playback_ops = {
+static const struct snd_pcm_ops snd_ad1816a_playback_ops = {
 	.open =		snd_ad1816a_playback_open,
 	.close =	snd_ad1816a_playback_close,
 	.ioctl =	snd_pcm_lib_ioctl,
@@ -664,7 +664,7 @@ static struct snd_pcm_ops snd_ad1816a_playback_ops = {
 	.pointer =	snd_ad1816a_playback_pointer,
 };
 
-static struct snd_pcm_ops snd_ad1816a_capture_ops = {
+static const struct snd_pcm_ops snd_ad1816a_capture_ops = {
 	.open =		snd_ad1816a_capture_open,
 	.close =	snd_ad1816a_capture_close,
 	.ioctl =	snd_pcm_lib_ioctl,