net: dsa: Fix network device registration order

We cannot be registering the network device first, then setting its
carrier off and finally connecting it to a PHY, doing that leaves a
window during which the carrier is at best inconsistent, and at worse
the device is not usable without a down/up sequence since the network
device is visible to user space with possibly no PHY device attached.

Re-order steps so that they make logical sense. This fixes some devices
where the port was not usable after e.g: an unbind then bind of the
driver.

Fixes: 0071f56e ("dsa: Register netdev before phy")
Fixes: 91da11f8

 ("net: Distributed Switch Architecture protocol support")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>