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 stratosk's method of calculating new freq

sometimes, interactive can stop reacting to load changes. also use cpufreq_relation_c to select the cloest frequency in the frequency table.

Change-Id: Ibadc149d9e16e8ea9a08384b9646c42516f6b493