[ALSA] hda-codec - Control SPDIF as slave

Add SPDIF playback switch to the slave element list so that it
can be toggled via the master control as well.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/pci/hda/patch_realtek.c

@@ -1492,6 +1492,7 @@ static const char *alc_slave_sws[] = {
 	"Headphone Playback Switch",
 	"Speaker Playback Switch",
 	"Mono Playback Switch",
+	"IEC958 Playback Switch",
 	NULL,
 };
 

sound/pci/hda/patch_sigmatel.c

@@ -873,6 +873,7 @@ static const char *slave_sws[] = {
 	"Speaker Playback Switch",
 	"External Speaker Playback Switch",
 	"Speaker2 Playback Switch",
+	"IEC958 Playback Switch",
 	NULL
 };