net: dsa: lantiq: Switch to use dev_err_probe() helper

dev_err() can be replace with dev_err_probe() which will check if error
code is -EPROBE_DEFER.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>