sysfs: Kill unused sysfs_sb variable.

Now that there are no more users we can remove
the sysfs_sb variable.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/sysfs/mount.c

@@ -23,7 +23,6 @@
 
 
 static struct vfsmount *sysfs_mount;
-struct super_block * sysfs_sb = NULL;
 struct kmem_cache *sysfs_dir_cachep;
 
 static const struct super_operations sysfs_ops = {
@@ -50,7 +49,6 @@ static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_magic = SYSFS_MAGIC;
 	sb->s_op = &sysfs_ops;
 	sb->s_time_gran = 1;
-	sysfs_sb = sb;
 
 	/* get root inode, initialize and unlock it */
 	mutex_lock(&sysfs_mutex);

fs/sysfs/sysfs.h

@@ -115,7 +115,6 @@ struct sysfs_addrm_cxt {
  * mount.c
  */
 extern struct sysfs_dirent sysfs_root;
-extern struct super_block *sysfs_sb;
 extern struct kmem_cache *sysfs_dir_cachep;
 
 /*