ALSA: hda - add support for Conexant CX20584

The Conexant CX20584 with 141f:5068 seems compatible with other
cxt5066 code.  Just add the missing id.

Tested-by: Cristopher Camacho Leandro <ccamacho@linuxmail.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>