ocfs2/xattr: Restore not_found in xis

During an xattr set, when we move a xattr which was stored in inode to the
outside bucket, we have to delete it and it will use the old value of
xis->not_found. xis->not_found is removed by ocfs2_calc_xattr_set_need
though, so we must restore it.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>