arm: dts: k3-am654-base-board: Add ICSSG2 Ethernet support

ICSSG2 provides dual Gigabit Ethernet support.
Add ICSSG2 ethernet node to an overlay k3-am654-icssg2.dtso

Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Acked-by: Ravi Gunasekaran <r-gunasekaran@ti.com>