[ALSA] remove duplicate field initialization

au88x0 driver
Remove duplicate (and inconsistent) initialization of the iface field.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

sound/pci/au88x0/au88x0_pcm.c

@@ -488,7 +488,6 @@ static snd_kcontrol_new_t snd_vortex_mixer_spdif[] __devinitdata = {
 		.put =		snd_vortex_spdif_put,
 	},
 	{
-		.iface =	SNDRV_CTL_ELEM_IFACE_MIXER,
 		.access =	SNDRV_CTL_ELEM_ACCESS_READ,
 		.iface =	SNDRV_CTL_ELEM_IFACE_PCM,
 		.name =		SNDRV_CTL_NAME_IEC958("",PLAYBACK,CON_MASK),