ath5k: use positive logic for HP laptop LEDs

Helge Deller reports that HP laptops (NC4010 and NC6000) use active-
high signals to turn on the LEDs.  Previous code used active-low for
all devices.

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>