dt-bindings: net: renesas,rzv2h-gbeth: Document Renesas RZ/G3L SoC

dt-bindings: net: renesas,rzv2h-gbeth: Document Renesas RZ/G3L SoC

Add device tree binding support for the Gigabit Ethernet (GBETH) IP on
Renesas RZ/G3L SoC. This SoC uses different Synopsys DesignWare MAC
version 5.30 compared to RZ/G3E.

RZ/G3L requires an extra clock compared to RZ/G3E and has pps interrupts.

Add a new compatible string "renesas,r9a08g046-gbeth" for RZ/G3L SoC and
update the schema to handle hardware differences between SoC variants.

Extend the base snps,dwmac.yaml schema to accommodate the PPS interrupts.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://patch.msgid.link/20260131161250.5047-2-biju.das.jz@bp.renesas.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>