cpufreq: interactive: Implement cluster-based min_sample_time

min_sample_time needs to be cluster-based to match
above_hispeed_delay. If each CPU keeps making local decisions, it's
possible min_sample_time is not correctly enforced at cluster level,
which results in undesired frequency drops.

Change-Id: I3eb24971b5d57260426f4932f37bb9ec170c3e42
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>