vfs: rename: move d_move() up

Move the d_move() in vfs_rename_dir() up, similarly to how it's done in
vfs_rename_other().  The next patch will consolidate these two functions
and this is the only structural difference between them.

I'm not sure if doing the d_move() after the dput is even valid.  But there
may be a logical explanation for that.  But moving the d_move() before the
dput() (and the mutex_unlock()) should definitely not hurt.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>