mm/damon: return void from damon_set_schemes()

mm/damon: return void from damon_set_schemes()

There is no point in returning an int from damon_set_schemes().  It always
returns 0 which is meaningless for the caller, so change it to return void
directly.

Link: https://lkml.kernel.org/r/1663341635-12675-1-git-send-email-kaixuxia@tencent.com
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>