[ALSA] Add const prefix

Control Midlevel
Add const prefix to snd_kcontrol_new_t pointer for better protection.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/control.c b/sound/core/control.c
index 4e39a21..227f3cf 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -215,7 +215,7 @@
  *
  * Returns the pointer of the newly generated instance, or NULL on failure.
  */
-snd_kcontrol_t *snd_ctl_new1(snd_kcontrol_new_t * ncontrol, void *private_data)
+snd_kcontrol_t *snd_ctl_new1(const snd_kcontrol_new_t * ncontrol, void *private_data)
 {
 	snd_kcontrol_t kctl;
 	unsigned int access;