ALSA: i2c: Constify snd_kcontrol_new items

Most of snd_kcontrol_new definitions are read-only and passed as-is.
Let's declare them as const for further optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-35-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/i2c/cs8427.c b/sound/i2c/cs8427.c
index bac4f00..8634d4f 100644
--- a/sound/i2c/cs8427.c
+++ b/sound/i2c/cs8427.c
@@ -459,7 +459,7 @@ static int snd_cs8427_spdif_mask_get(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
-static struct snd_kcontrol_new snd_cs8427_iec958_controls[] = {
+static const struct snd_kcontrol_new snd_cs8427_iec958_controls[] = {
 {
 	.iface =	SNDRV_CTL_ELEM_IFACE_PCM,
 	.info =		snd_cs8427_in_status_info,