mm/kmemleak: make create_object return void

No caller cares about the return value of create_object(), so make it
return void.

Link: https://lkml.kernel.org/r/20220901023007.3471887-1-liushixin2@huawei.com


Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>