ALSA: hda/realtek - Skip invalid digital out pins

ALSA: hda/realtek - Skip invalid digital out pins

commit 51e4152a969aa6d2306492ebf143932dcb535c9b upstream.

Some BIOS report invalid pins as digital output pins.  The driver checks
the connection but it doesn't do it fully correctly, and it leaves some
undefined value as the audio-out widget, which makes the driver spewing
warnings.  This patch fixes the issue.

Reference: https://bugzilla.novell.com/show_bug.cgi?id=727348

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>