ALSA: drivers: Constify snd_ac97_bus_ops definitions

Now snd_ac97_bus() takes the const ops pointer, so we can define the
snd_ac97_bus_ops locally as const as well for further optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-27-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/ml403-ac97cr.c

@@ -1172,7 +1172,7 @@ snd_ml403_ac97cr_mixer(struct snd_ml403_ac97cr *ml403_ac97cr)
 	struct snd_ac97_bus *bus;
 	struct snd_ac97_template ac97;
 	int err;
-	static struct snd_ac97_bus_ops ops = {
+	static const struct snd_ac97_bus_ops ops = {
 		.write = snd_ml403_ac97cr_codec_write,
 		.read = snd_ml403_ac97cr_codec_read,
 	};