[ALSA] hda-codec - Adapt eeepc p701 mixer for virtual master control

Fix the line-out volume control of eeepc p701 to be a proper slave of
the virtual master control.

Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>