arm64: dts: ti: k3-j721s2: Add overlay to enable main CPSW2G with GESI

arm64: dts: ti: k3-j721s2: Add overlay to enable main CPSW2G with GESI

The MAIN CPSW2G instance of CPSW on J721S2 SoC can be enabled with the GESI
Expansion Board connected to the J7 Common-Proc-Board. Use the overlay
to enable this.

Add alias for the MAIN CPSW2G port to enable kernel to fetch MAC address
directly from U-Boot.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
Link: https://lore.kernel.org/r/20230726065407.378455-3-s-vadapalli@ti.com
Signed-off-by: Nishanth Menon <nm@ti.com>