[ALSA] hda-codec - add support for analog loopback to STAC9204/9205/922x/927x

The analog loopback routes the sound just before it enters ADC0
to output of DAC0.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>