This patch addes the support of the independent 'Headphone' volume
control to the generic codec parser.  Some codecs (e.g. Conexant)
have separate connections to the headphone and the independent amp
adjustment is needed.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@suse.cz>