vfs: remove unused i_op->rename

No in-tree uses remain.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/Documentation/filesystems/directory-locking b/Documentation/filesystems/directory-locking
index c314bad..4e32cb9 100644
--- a/Documentation/filesystems/directory-locking
+++ b/Documentation/filesystems/directory-locking
@@ -19,7 +19,7 @@
 
 4) rename() that is _not_ cross-directory.  Locking rules: caller locks
 the parent and finds source and target.  In case of exchange (with
-RENAME_EXCHANGE in rename2() flags argument) lock both.  In any case,
+RENAME_EXCHANGE in flags argument) lock both.  In any case,
 if the target already exists, lock it.  If the source is a non-directory,
 lock it.  If we need to lock both, lock them in inode pointer order.
 Then call the method.  All locks are exclusive.