ALSA: constify functions in ac97

Signed-off-by: Hanno Boeck <hanno@hboeck.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/ac97_codec.h

@@ -477,7 +477,7 @@ struct snd_ac97_template {
 
 struct snd_ac97 {
 	/* -- lowlevel (hardware) driver specific -- */
-	struct snd_ac97_build_ops * build_ops;
+	const struct snd_ac97_build_ops *build_ops;
 	void *private_data;
 	void (*private_free) (struct snd_ac97 *ac97);
 	/* --- */

sound/pci/ac97/ac97_codec.c

@@ -1961,7 +1961,7 @@ static int snd_ac97_dev_disconnect(struct snd_device *device)
 }
 
 /* build_ops to do nothing */
-static struct snd_ac97_build_ops null_build_ops;
+static const struct snd_ac97_build_ops null_build_ops;
 
 #ifdef CONFIG_SND_AC97_POWER_SAVE
 static void do_update_power(struct work_struct *work)