ALSA: hda - Add EAPD control to Conexnat auto-parser

Added the vmaster hook for controlling EAPD dynamically to Conexant
auto-parser.  When the Master is muted, EAPDs are turned off as well.
This will fix the missing mute-LED control on some machines in
addition to the more power-saving in the auto-parser mode.

Signed-off-by: Takashi Iwai <tiwai@suse.de>