Documentation/filesystems/Locking: ->get_sb() is long gone

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Documentation/filesystems/Locking

@@ -164,8 +164,6 @@ the block device inode.  See there for more details.
 
 --------------------------- file_system_type ---------------------------
 prototypes:
-	int (*get_sb) (struct file_system_type *, int,
-		       const char *, void *, struct vfsmount *);
 	struct dentry *(*mount) (struct file_system_type *, int,
 		       const char *, void *);
 	void (*kill_sb) (struct super_block *);