cpufreq: governors: Fix jiffies/cputime mixup (revisited)

This change was made by commit 8636fd28 (cpufreq: fix jiffies/cputime
mixup in conservative/ondemand governors) before, but then it has
been reverted inadvertently by commit 4471a34f (cpufreq: governors:
remove redundant code).

The changelog of commit 8636fd28's says:

  The function get_cpu_idle_time_jiffy in both the conservative and
  ondemand governors use jiffies_to_usecs to convert a cputime value
  to usecs which gives the wrong value on architectures where cputime
  and jiffies use different units.  Only matters if NO_HZ is
  disabled, since otherwise get_cpu_idle_time_us should already
  return a valid value, and get_cpu_idle_time_jiffy isn't actually
  called.

Since now we have only one common get_cpu_idle_time_jiffy() used by
both governors in question, modify it along the lines of commit
8636fd28 to restore the correct behavior.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NViresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/cpufreq_governor.c

@@ -45,9 +45,9 @@ static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
 
 	idle_time = cur_wall_time - busy_time;
 	if (wall)
-		*wall = jiffies_to_usecs(cur_wall_time);
+		*wall = cputime_to_usecs(cur_wall_time);
 
-	return jiffies_to_usecs(idle_time);
+	return cputime_to_usecs(idle_time);
 }
 
 u64 get_cpu_idle_time(unsigned int cpu, u64 *wall)