soc: fsl: dpio: Use after free in dpaa2_dpio_remove()

The dpaa2_io_down(priv->io) call frees "priv->io" so I've shifted the
code around a little bit to avoid the use after free.

Fixes: 991e8732

 ("soc: fsl: dpio: use a cpumask to identify which cpus are unused")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Li Yang <leoyang.li@nxp.com>