kernel/cpuset: current_cpuset_is_being_rebound can be boolean

Make current_cpuset_is_being_rebound return bool due to this particular
function only using either one or zero as its return value.

No functional change.

Link: http://lkml.kernel.org/r/1513266622-15860-4-git-send-email-baiyaowei@cmss.chinamobile.com


Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>