cpufreq/zzmoove: added responsiveness_sampling_rate

- added tuneable for responsiveness_sampling_rate (0 = disabled)
	when at very low frequencies the user usually ends up waiting
	several samples/cycles before the frequency is boosted enough
	to eliminate touch-lag. so at the default of 100ms, that could be
	a quarter of a second spent at agonizingly slow speeds, which
	translates to lag every time the user starts to interact with
	the screen.

	so now with this tuneable, in addition to increasing the up
	threshold, the user can also reduce (or increase, if they are crazy)
	the sampling rate for very low frequencies.

	note that this can be set to 0 to be ignored, and so can the
	up threshold, which effectively means you can enforce either
	or both of those tuneables to help reduce lag along with the
	frequency threshold defined in responsiveness_freq.