ALSA: hda - Allow digital-only I/O on ALC262 codec

Some laptops like VAIO have multiple codecs and uses ALC262 only for
the SPIDF output without analog I/O.  So far, the codec-parser assumes
the presence of analog I/O and returned an error for such a case.

This patch adds some hacks to allow the digital-only configuration for
ALC262.

Signed-off-by: Takashi Iwai <tiwai@suse.de>