[ALSA] Show currectly selected widget in proc_read for hda driver

HDA generic driver
During debugging for cm9880 multi-channel playback, I added the * after
the currently selected widget, mixer widget doesn't need this but other
3 widget types need it.

Signed-off-by: ChenLi Tien <cltien@cmedia.com.tw>
Signed-off-by: Takashi Iwai <tiwai@suse.de>