ALSA: ens137x: Replace with DEFINE_SIMPLE_DEV_PM_OPS()

Use the new DEFINE_SIMPLE_DEV_PM_OPS() instead of SIMPLE_DEV_PM_OPS()
for code-simplification. We need no longer CONFIG_PM_SLEEP ifdefs.

For building properly, add the dummy functions for
snd_ak4531_suspend/resume() functions, too.

Just a cleanup, no functional changes.

Signed-off-by: Takashi Iwai <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

include/sound/ak4531_codec.h

···
 #ifdef CONFIG_PM
 void snd_ak4531_suspend(struct snd_ak4531 *ak4531);
 void snd_ak4531_resume(struct snd_ak4531 *ak4531);
+#else
+static inline void snd_ak4531_suspend(struct snd_ak4531 *ak4531) {}
+static inline void snd_ak4531_resume(struct snd_ak4531 *ak4531) {}
 #endif
 
 #endif /* __SOUND_AK4531_CODEC_H */

sound/pci/ens1370.c

···
 	outl(ensoniq->cssr, ES_REG(ensoniq, STATUS));
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int snd_ensoniq_suspend(struct device *dev)
 {
 	struct snd_card *card = dev_get_drvdata(dev);
···
 	return 0;
 }
 
-static SIMPLE_DEV_PM_OPS(snd_ensoniq_pm, snd_ensoniq_suspend, snd_ensoniq_resume);
-#define SND_ENSONIQ_PM_OPS	&snd_ensoniq_pm
-#else
-#define SND_ENSONIQ_PM_OPS	NULL
-#endif /* CONFIG_PM_SLEEP */
+static DEFINE_SIMPLE_DEV_PM_OPS(snd_ensoniq_pm, snd_ensoniq_suspend, snd_ensoniq_resume);
 
 static int snd_ensoniq_create(struct snd_card *card,
 			      struct pci_dev *pci)
···
 	.id_table = snd_audiopci_ids,
 	.probe = snd_audiopci_probe,
 	.driver = {
-		.pm = SND_ENSONIQ_PM_OPS,
+		.pm = &snd_ensoniq_pm,
 	},
 };