ocfs2: Move ocfs2_complete_reflink to the right place.

As its name ocfs2_complete_reflink indicates, it should
be called after all the work for reflink is done, so
it really should be called after we reflink xattr
successfully.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Tested-by: Tristan Ye <tristan.ye@oracle.com>