[ALSA] HDA: Fix headphone mute issue on non-eapd Conexant systems

This patch fixes an automute code issue for systems that do not rely
on eapd support.

Signed-off-by: Tobin Davis <tdavis@dsl-only.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>