arm64: dts: ti: k3-am62: disable "cpsw3g" in SoC file and enable in board file

arm64: dts: ti: k3-am62: disable "cpsw3g" in SoC file and enable in board file

Following the existing convention of disabling nodes in the SoC file and
enabling only the required ones in the board file, disable "cpsw3g" node
in the SoC file "k3-am62-main.dtsi" and enable it in the board (or board
include) files:
a) k3-am62-lp-sk.dts
b) k3-am62-phycore-som.dtsi
c) k3-am625-beagleplay.dts
d) k3-am625-sk-common.dtsi

Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Link: https://patch.msgid.link/20251015111344.3639415-2-s-vadapalli@ti.com
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>