arm: dts: ls1028a updates for network interfaces

Defines LS1028A RDB SGMII port, QDS RGMII port.

Signed-off-by: Alex Marginean <alexm.osslist@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>