Revert "kernfs: remove KERNFS_ACTIVE_REF and add kernfs_lockdep()"

This reverts commit a69d001cfc712b96ec9d7ba44d6285702a38dabf.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 42ad32f..232f1a6 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -34,6 +34,7 @@
 };
 
 #define KERNFS_TYPE_MASK	0x000f
+#define KERNFS_ACTIVE_REF	KERNFS_FILE
 #define KERNFS_FLAG_MASK	~KERNFS_TYPE_MASK
 
 enum kernfs_node_flag {