cpufreq: create a helper function to get CPU utilization. Picked from @stratosk

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
cpufreq: export the cpu load across cores to the policy struct. On Performance governor let's emulate a constant 100% load (in this Kernel's case it will make all cores online, which is kinda the purpose of a performance governor isn't it?).

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
cpufreq: Initial CPU utilization should be 0

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
cpufreq: Introduce new relation for freq selection

Introduce CPUFREQ_RELATION_C for frequency selection.
It selects the frequency with the minimum euclidean distance
to target. In case of equal distance between 2 frequencies,
it will select the greater freq.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>