dt-bindings: net: ravb : Add support for r8a7745 SoC

Add a new compatible string for the RZ/G1E (R8A7745) SoC.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Acked-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>