ALSA: usb: 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/usb/misc/ua101.c

@@ -890,7 +890,7 @@ static snd_pcm_uframes_t playback_pcm_pointer(struct snd_pcm_substream *subs)
 	return ua101_pcm_pointer(ua, &ua->playback);
 }
 
-static struct snd_pcm_ops capture_pcm_ops = {
+static const struct snd_pcm_ops capture_pcm_ops = {
 	.open = capture_pcm_open,
 	.close = capture_pcm_close,
 	.ioctl = snd_pcm_lib_ioctl,
@@ -903,7 +903,7 @@ static struct snd_pcm_ops capture_pcm_ops = {
 	.mmap = snd_pcm_lib_mmap_vmalloc,
 };
 
-static struct snd_pcm_ops playback_pcm_ops = {
+static const struct snd_pcm_ops playback_pcm_ops = {
 	.open = playback_pcm_open,
 	.close = playback_pcm_close,
 	.ioctl = snd_pcm_lib_ioctl,