dt-bindings: net: renesas,etheravb: Add support for R-Car V4M

Document support for the Renesas Ethernet AVB (EtherAVB-IF) block in the
Renesas R-Car V4M (R8A779H0) SoC.

Signed-off-by: Thanh Quan <thanh.quan.xn@renesas.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/0212b57ba1005bb9b5a922f8f25cc67a7bc15f30.1709631152.git.geert+renesas@glider.be


Signed-off-by: Jakub Kicinski <kuba@kernel.org>