cpufreq:LAB:core: Redesign of LAB code to work on top of ONDEMAND governor

cpufreq:LAB:core: Redesign of LAB code to work on top of ONDEMAND governor

The code for LAB has been redesigned to be able to work on top of Ondemand
governor.
Previous version of LAB - the one which used the polynomial approximation
has been replaced with more readable approach.
The LAB control approach is now read from device tree.

User is allowed to specify following operations (based on load and number of
idle CPUs):
- Force a particular frequency
- Explicitly enable boost for a specific kind of load
- Use ondemand governor

By using ondemand one can be sure that for non critical frequencies correct
value will be chosen.
LAB, which works on top of it, can clamp the freq (an thereof power management)
or explicitly enable boost.

Change-Id: Ieaf84d245463edf90fb2baaf825c0534970eab7e
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>