arm: dts: aspeed: tiogapass: Enable second MAC

Tioga Pass reference design includes Intel I210 Ethernet controller
connected to the BMC with NC/SI.

MAC readout is not supported.

Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-by: Vijay Khemka <vijaykhemkalinux@gmail.com>
Tested-by: Vijay Khemka <vijaykhemkalinux@gmail.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>