cpufreq: interactive: Simplify frequency calculations

Previously, complicated calculations led to oscillating cpu
frequencies that ruined user experience even on high-end
devices. Revert to the classic calculations based on a
percentage of current max frequency.  This way, we're using
freqs more evenly and much more predictable.

Change-Id: Id7898618607f0e26b272e3c74932a92380e3db7a
cpufreq: interactive: Consider changed min limit a frequency boost

A changed policy->min can safely be considered a frequency boost.
Process this change analogous to the cpufreq_interactive_boost()
routine.

Change-Id: Ie4ca2be2dad0f5bd541c2b79afee3bad3a349d80
cpufreq: interactive: Honor boosted state in several timer calculations

Change-Id: If03da12c52d89a5293e32ac918db44a00ef34884