[ALSA] at73c213 - Use common callback

Use snd_ctl_boolean_mono_info callback to simplify.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@perex.cz>

sound/spi/at73c213.c

@@ -536,16 +536,7 @@ static int snd_at73c213_stereo_put(struct snd_kcontrol *kcontrol,
 	return retval;
 }
 
-static int snd_at73c213_mono_switch_info(struct snd_kcontrol *kcontrol,
-				  struct snd_ctl_elem_info *uinfo)
-{
-	uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
-	uinfo->count = 1;
-	uinfo->value.integer.min = 0;
-	uinfo->value.integer.max = 1;
-
-	return 0;
-}
+#define snd_at73c213_mono_switch_info	snd_ctl_boolean_mono_info
 
 static int snd_at73c213_mono_switch_get(struct snd_kcontrol *kcontrol,
 				 struct snd_ctl_elem_value *ucontrol)