cpufreq: interactive: Reset last evaluated jiffy in idle callback

When CPU has been busy for a long time, last evaluated jiffy will be
quite behind because the timer would have been canceled. We don't want
to schedule a timer to fire in the past as load will always be 100%.

Reset last evaluated jiffy so that timer will be scheduled for the
next window.

Change-Id: Ie25e65eab1f16acdeda267987ca605d653f1f32a
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>