KLAPSE : Make default flow_freq value configurable at compile time from klapse.h

- NOTE : Flow freq is a device-dependent timeout value. It depends on how fast KCAL reacts to a change in values, or in other words, how fast can you change colors in KCAL without having them not appear on screen (aka "RGB frame skips")
 - NOTE : Flow freq should be reduced if KCAL reacts faster, left at 360 is unsure, increased for very high latencies (usually in MDSS)
 - NOTE : Flow freq can be changed at runtime as well, so developers can find the perfect value that isn't too slow and isn't too sudden either
 - NOTE : Flow freq is 360 (ms) by default, because of my testing on OnePlus 6 (enchilada) on stock ROM with custom display calibration
 - NOTE : More GPU pulses can help most devices refresh KCAL faster, and indirectly "flow" smoother