dsa: Register netdev before phy

When the phy is connected, an info message is printed. If the netdev
it is attached to has not been registered yet, the name
'uninitialised' in the output. By registering the netdev first, then
connecting they phy, we can avoid this.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>