dt-bindings: clock: renesas,r9a09g077/87: Add Ethernet clock IDs

dt-bindings: clock: renesas,r9a09g077/87: Add Ethernet clock IDs

Add clock definitions for Ethernet (ETCLK A-E) to both R9A09G077 and
R9A09G087 SoCs. These definitions are required for describing Ethernet
devices in DT.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250904071954.3176806-2-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>