[ALSA] Add suspend callback

AC97 Codec Core
Add suspend callback for each codec patch.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/ac97_codec.h

@@ -426,6 +426,7 @@ struct snd_ac97_build_ops {
 	int (*build_spdif) (ac97_t *ac97);
 	int (*build_post_spdif) (ac97_t *ac97);
 #ifdef CONFIG_PM
+	void (*suspend) (ac97_t *ac97);
 	void (*resume) (ac97_t *ac97);
 #endif
 };

sound/pci/ac97/ac97_codec.c

@@ -2163,6 +2163,8 @@ static void snd_ac97_powerdown(ac97_t *ac97)
  */
 void snd_ac97_suspend(ac97_t *ac97)
 {
+	if (ac97->build_ops->suspend)
+		ac97->build_ops->suspend(ac97);
 	snd_ac97_powerdown(ac97);
 }