cpufreq: interactive_pro: Align timer windows for all CPUs

It's more advantageous to evaluate all CPUs at same time so that
interactive governor gets a complete picture of the load on
each CPU at a specific time. It could also reduce number of speed
changes made if there are many CPUs controlled by same policy.

Change-Id: I4cfa5027b7a8c647f34893215573dc1fcd6428d5
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>