mm/compaction: remove unnecessary return for void function

Remove unnecessary return for void function

Link: https://lkml.kernel.org/r/20230804110454.2935878-8-shikemeng@huaweicloud.com


Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>