drivers/base/node.c: fix compaction sysfs file leak
In the Linux kernel, the following vulnerability has been resolved:

drivers/base/node.c: fix compaction sysfs file leak

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.