Always disable all LEDs before updating them.

This should make sure the PWMs for red/green/blue always run in sync,
not only when switching between the various light types
(attention/battery/notification).

Change-Id: I0d743f31b645445da04436fd8ab8e8fdec39dfb9
Clean up lights module code.

Change-Id: Ic195efafde9dba965727d055576df5f6b2a1431b
The kernel now ensures to restart PWM on color change.

Thus, there's no need to do it in user space anymore.
Also, adapt grpfreq and grppwm calculations and comments to actual
in-kernel implementation.

Change-Id: I657888391679c4b817e0c60e1a6e520e4adafba4