sysfs: Remove first pass at shadow directory support

While shadow directories appear to be a good idea, the current scheme
of controlling their creation and destruction outside of sysfs appears
to be a locking and maintenance nightmare in the face of sysfs
directories dynamically coming and going.  Which can now occur for
directories containing network devices when CONFIG_SYSFS_DEPRECATED is
not set.

This patch removes everything from the initial shadow directory support
that allowed the shadow directory creation to be controlled at a higher
level.  So except for a few bits of sysfs_rename_dir everything from
commit b592fcfe7f is now gone.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/sysfs/mount.c

@@ -20,7 +20,7 @@ struct kmem_cache *sysfs_dir_cachep;
 
 static const struct super_operations sysfs_ops = {
 	.statfs		= simple_statfs,
-	.drop_inode	= sysfs_delete_inode,
+	.drop_inode	= generic_delete_inode,
 };
 
 struct sysfs_dirent sysfs_root = {