ALSA: drivers: 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/drivers/aloop.c

@@ -750,7 +750,7 @@ static int loopback_close(struct snd_pcm_substream *substream)
 	return 0;
 }
 
-static struct snd_pcm_ops loopback_playback_ops = {
+static const struct snd_pcm_ops loopback_playback_ops = {
 	.open =		loopback_open,
 	.close =	loopback_close,
 	.ioctl =	snd_pcm_lib_ioctl,
@@ -763,7 +763,7 @@ static struct snd_pcm_ops loopback_playback_ops = {
 	.mmap =		snd_pcm_lib_mmap_vmalloc,
 };
 
-static struct snd_pcm_ops loopback_capture_ops = {
+static const struct snd_pcm_ops loopback_capture_ops = {
 	.open =		loopback_open,
 	.close =	loopback_close,
 	.ioctl =	snd_pcm_lib_ioctl,

sound/drivers/ml403-ac97cr.c

@@ -759,7 +759,7 @@ static int snd_ml403_ac97cr_capture_close(struct snd_pcm_substream *substream)
 	return 0;
 }
 
-static struct snd_pcm_ops snd_ml403_ac97cr_playback_ops = {
+static const struct snd_pcm_ops snd_ml403_ac97cr_playback_ops = {
 	.open = snd_ml403_ac97cr_playback_open,
 	.close = snd_ml403_ac97cr_playback_close,
 	.ioctl = snd_pcm_lib_ioctl,
@@ -770,7 +770,7 @@ static struct snd_pcm_ops snd_ml403_ac97cr_playback_ops = {
 	.pointer = snd_ml403_ac97cr_pcm_pointer,
 };
 
-static struct snd_pcm_ops snd_ml403_ac97cr_capture_ops = {
+static const struct snd_pcm_ops snd_ml403_ac97cr_capture_ops = {
 	.open = snd_ml403_ac97cr_capture_open,
 	.close = snd_ml403_ac97cr_capture_close,
 	.ioctl = snd_pcm_lib_ioctl,