Knock control : Reapply rate as % of aggression

[OrchardPerformance]

Current method of degrees/second is too slow at low load and too fast at high load. (also hard to pick a reasonable base value).

The aggression was designed to vary the size of the retard steps with the ignition advance, using a % of aggression to do the reapply will also allow it to scale with the size of the retard steps.

Suggest we use a base value of about 30% of the aggression value, that way we will re-advance at ~1/3rd any step calculated for retard.