ALSA: hda - Rewrite the mute-LED control with vmaster hook for ALC269

We've had ugly static handling of the mute-LED with a powersave hook
for ALC269 HP laptops just like done in patch_sigmatel.c.  This is now
rewritten with the new vmaster hook and a fixup code.

For that, the new fixup action, ALC_FIXUP_ACT_BUILD, is introduced.
It's called after build_controls is called.  The reason of this new
action is that vmaster hook must be added at this stage (not in init
or probe).

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