ALSA: control: Make snd_ctl_find_id() argument const

The id object passed to snd_ctl_find_id() is only read, and we can
mark it with const gracefully.

Link: https://lore.kernel.org/r/20230718141304.1032-9-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/control.h

@@ -141,7 +141,7 @@ int snd_ctl_rename_id(struct snd_card * card, struct snd_ctl_elem_id *src_id, st
 void snd_ctl_rename(struct snd_card *card, struct snd_kcontrol *kctl, const char *name);
 int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id, int active);
 struct snd_kcontrol *snd_ctl_find_numid(struct snd_card * card, unsigned int numid);
-struct snd_kcontrol *snd_ctl_find_id(struct snd_card * card, struct snd_ctl_elem_id *id);
+struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card, const struct snd_ctl_elem_id *id);
 
 int snd_ctl_create(struct snd_card *card);
 

sound/core/control.c

@@ -858,7 +858,7 @@ EXPORT_SYMBOL(snd_ctl_find_numid);
  *
  */
 struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
-				     struct snd_ctl_elem_id *id)
+				     const struct snd_ctl_elem_id *id)
 {
 	struct snd_kcontrol *kctl;