[ALSA] HDA-Intel: Fix headphone squeal on Conexant audio

This patch fixes the headphone squeal and noise on Conexant CX20551
(Waikiki) audio.

Signed-off-by: Tobin Davis <gruemaster@email.uophx.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>