ALSA: hda - Fix wrong auto-mute type for Acer Aspire-one

The auto-mute setup for Acer Aspire-one with ALC268 was set wrongly
during the clean-up of auto-mute function.  Fixed now.

Tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>