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: Ia2ec2ad9b7a8d715d4408c924d6762b7e532e4b4
Reviewed-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>