dtb: xgene: Add second SGMII based 1G interface node

- Added new SGMII node for port 1
- Added port-id field

Signed-off-by: Keyur Chudgar <kchudgar@apm.com>
Signed-off-by: Iyappan Subramanian <isubramanian@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>