ALSA: i2c: Constify snd_device_ops definitions

Now we may declare const for snd_device_ops definitions, so let's do
it for optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-7-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/i2c/other/ak4114.c

@@ -71,7 +71,7 @@ int snd_ak4114_create(struct snd_card *card,
 	struct ak4114 *chip;
 	int err = 0;
 	unsigned char reg;
-	static struct snd_device_ops ops = {
+	static const struct snd_device_ops ops = {
 		.dev_free =     snd_ak4114_dev_free,
 	};