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
Fix android.os.cts.BuildVersionTest failure

Change-Id: Ic04d359be9b74d7f3afadbf09d2c4e0563d87d18