sched/core: Fix comment regarding nr_iowait_cpu() and get_iowait_load()

sched/core: Fix comment regarding nr_iowait_cpu() and get_iowait_load()

The comment related to nr_iowait_cpu() and get_iowait_load() confuses
cpufreq with cpuidle and is not very useful for this reason, so fix it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux PM <linux-pm@vger.kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: e33a9bba85a8 "sched/core: move IO scheduling accounting from io_schedule_timeout() into scheduler"
Link: http://lkml.kernel.org/r/3803514.xkx7zY50tF@aspire.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>