ALSA: sis7019: 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/pci/sis7019.c

@@ -872,7 +872,7 @@ static int sis_pcm_capture_prepare(struct snd_pcm_substream *substream)
 	return 0;
 }
 
-static struct snd_pcm_ops sis_playback_ops = {
+static const struct snd_pcm_ops sis_playback_ops = {
 	.open = sis_playback_open,
 	.close = sis_substream_close,
 	.ioctl = snd_pcm_lib_ioctl,
@@ -883,7 +883,7 @@ static struct snd_pcm_ops sis_playback_ops = {
 	.pointer = sis_pcm_pointer,
 };
 
-static struct snd_pcm_ops sis_capture_ops = {
+static const struct snd_pcm_ops sis_capture_ops = {
 	.open = sis_capture_open,
 	.close = sis_substream_close,
 	.ioctl = snd_pcm_lib_ioctl,