arm64: dts: ti: k3-am62a7: Add overlay for second CPSW3G Port

The SK-Ethernet-DC01 Add-On Ethernet Card for AM62A-SK board supports
RGMII mode.

Add overlay to enable the second CPSW3G port in RGMII-RXID mode with the
Add-On Ethernet Card.

Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>