The VT1702 and VT1708S have a second S/PDIF output which is used to
connect to a HDMI transmitter.  This patch adds support for it.
Signed-off-by: NHarald Welte <HaraldWelte@viatech.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@perex.cz>