ALSA: core: Remove superfluous CONFIG_PM

Since the recent code change, the conditional build with CONFIG_PM is
calling only snd_power_sync_ref().  As a dummy function is provided
for this function, we can get rid of CONFIG_PM gracefully now.

Link: https://lore.kernel.org/r/20240510125128.6058-1-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/init.c

@@ -550,9 +550,7 @@ void snd_card_disconnect(struct snd_card *card)
 		clear_bit(card->number, snd_cards_lock);
 	}
 
-#ifdef CONFIG_PM
 	snd_power_sync_ref(card);
-#endif
 }
 EXPORT_SYMBOL(snd_card_disconnect);