update_ts_time_stat currently updates idle time even if we are in iowait

update_ts_time_stat currently updates idle time even if we are in iowait
loop at the moment.  The only real users of the idle counter (via
get_cpu_idle_time_us) are CPU governors and they expect to get cumulative
time for both idle and iowait times.  The value (idle_sleeptime) is also
printed to userspace by print_cpu but it prints both idle and iowait times
so the idle part is misleading.

Let's clean this up and fix update_ts_time_stat to account both counters
properly and update consumers of idle to consider iowait time as well.  If
we do this we might use get_cpu_{idle,iowait}_time_us from other contexts
as well and we will get expected values.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Dave Jones <davej@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>