dt-bindings: net: renesas,etheravb: Document RZ/Five SoC

The Gigabit Ethernet IP block on the RZ/Five SoC is identical to one
found on the RZ/G2UL SoC. "renesas,r9a07g043-gbeth" compatible string
will be used on the RZ/Five SoC so to make this clear and to keep this
file consistent, update the comment to include RZ/Five SoC.

No driver changes are required as generic compatible string
"renesas,rzg2l-gbeth" will be used as a fallback on RZ/Five SoC.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: David S. Miller <davem@davemloft.net>