net: ixp4xx_eth: Return proper error for eth_init_one

Return PTR_ERR(port->phydev) instead of 1 if phy_connect failed.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>