cpufreq: Move get_cpu_idle_time() to cpufreq.c

Governors other than ondemand and conservative can also use
get_cpu_idle_time() and they aren't required to compile
cpufreq_governor.c. So, move these independent routines to
cpufreq.c instead.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Git-commit: 72a4ce340a7ebf39e1c6fdc8f5feb4f974d6c635
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[junjiew@codeaurora.org: update non-upstream files]
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>

Change-Id: I3227454599250011a19a752c962e3cacb1fb0301
cpufreq: interactive: Add max_freq_hysteresis feature

Previously known as sampling down factor, max_freq_hysteresis
extends the period that interactive governor will stay at policy->max.
This feature is to accomodate short idle periods in an otherwise very
intensive workload.

When the feature is enabled, it ensures that once a CPU goes to max
frequency, it doesn't reduce the frequency for max_freq_hysteresis
microseconds from the time it first goes to idle.

Change-Id: Ia54985cb554f63f8c22d0b554a0a0f2ed2be038f
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>

Conflicts:
	drivers/cpufreq/cpufreq_interactive.c