dt-bindings: rpc: renesas-rpc-if: Add support for the R8A779A0 RPC-IF

Add bindings for the R8A779A0 (R-Car V3U).

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20210922085831.5375-1-wsa+renesas@sang-engineering.com


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>