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>
cpufreq: interactive: use the new cpufreq relation

this selects the closest frequency to the new_freq instead of the lowest frequency at or above it, resulting in fairer scaling judgments.

Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>