ALSA: wss_lib: fix AZT2320 probe.

After the transition from cs4321_lib to wss_lib, azt2320 probe visits
snd_ad1848_probe during detection. It expects register 0 (LEFT_INPUT)
to be able to retain the value 0xaa during detection but AZT2320 does
not support MIC gain meaning it reads back as 0x8a instead.

Signed-off-by: Rene Herman <rene.herman@gmail.com>
Acked-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>