The callers are only interested in the actual zone, they don't care about
boundaries.  Return the zone instead to simplify.

Link: http://lkml.kernel.org/r/20200110183308.11849-1-david@redhat.comSigned-off-by: NDavid Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>