[ALSA] maestro3: Fix hw volume on HP OmniBook

Make the hw volume buttons work correctly on some HP OmniBook laptops.
The original quirk was apparently applied a bit too early and it was
also lacking some critial register writes. This improved sequence was
discovered by trial and error (like the original sequence). Tested and
found working on OB500 and OB6000 laptops.

Signed-off-by: Ville Syrjala <syrjala@sci.fi>
Signed-off-by: Takashi Iwai <tiwai@suse.de>