net: dsa: sja1105: Don't error out on disabled ports with no phy-mode

The sja1105_parse_ports_node function was tested only on device trees
where all ports were enabled. Fix this check so that the driver
continues to probe only with the ports where status is not "disabled",
as expected.

Fixes: 8aa9ebcc ("net: dsa: Introduce driver for NXP SJA1105 5-port L2 switch")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>