ALSA: hda - Add missing terminator in slave dig-out array

Added the missing terminator for ad1989b_slave_dig_outs[].

Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_analog.c

@@ -1885,8 +1885,8 @@ static hda_nid_t ad1988_capsrc_nids[3] = {
 #define AD1988_SPDIF_OUT_HDMI	0x0b
 #define AD1988_SPDIF_IN		0x07
 
-static hda_nid_t ad1989b_slave_dig_outs[2] = {
-	AD1988_SPDIF_OUT, AD1988_SPDIF_OUT_HDMI
+static hda_nid_t ad1989b_slave_dig_outs[] = {
+	AD1988_SPDIF_OUT, AD1988_SPDIF_OUT_HDMI, 0
 };
 
 static struct hda_input_mux ad1988_6stack_capture_source = {