dt-bindings: net: ravb : Add support for r8a7743 SoC

Add a new compatible string for the RZ/G1M (R8A7743) SoC.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>