sched: Change root_domain->overload type to int

sizeof(_Bool) is implementation defined, so let's just go with 'int' as
is done for other structures e.g. sched_domain_shared->has_idle_cores.

The local 'overload' variable used in update_sd_lb_stats can remain
bool, as it won't impact any struct layout and can be assigned to the
root_domain field.

Cc: vincent.guittot@linaro.org
Cc: mingo@redhat.com
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1530699470-29808-8-git-send-email-morten.rasmussen@arm.com