net: mdiobus: fix double put fwnode in the error path

If phy_device_register() or fwnode_mdiobus_phy_device_register()
fail, phy_device_free() is called, the device refcount is decreased
to 0, then fwnode_handle_put() will be called in phy_device_release(),
but in the error path, fwnode_handle_put() has already been called,
so set fwnode to NULL after fwnode_handle_put() in the error path to
avoid double put.

Fixes: cdde1560

 ("net: mdiobus: fix unbalanced node reference count")
Reported-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>