Compaction sysfs file is created via compaction_register_node in
register_node.  But we forgot to remove it in unregister_node.  Thus
compaction sysfs file is leaked.  Using compaction_unregister_node to fix
this issue.

Link: https://lkml.kernel.org/r/20220401070905.43679-1-linmiaohe@huawei.com
Fixes: ed4a6d7f ("mm: compaction: add /sys trigger for per-node memory compaction")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>