intel_idle: Propagate hot plug errors.

intel_idle: Propagate hot plug errors.

Orabug: 24810432

If a cpuidle registration error occurs during the hot plug notifier
callback, we should really inform the hot plug machinery instead of
just ignoring the error.  This patch changes the callback to properly
return on error.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 08820546e4c30c84d0a1f1a49df055e1719c07ea)
Signed-off-by: Brian Maly <brian.maly@oracle.com>