cpufreq: interactive: Honor boosted state when entering idle

The old logic didn't take the boosted state in account. Just
leave the comment intact because our temporary min is not
the regular policy->min it refers to.
cpufreq: interactive: fix compiling warnings
cpufreq: interactive: Initialize spinlocks

These were missing in commit 8fbac318173082918312d6a4ceacf63376797c52,
"cpufreq: interactive: Use frequency dependent per cpu timings".