ravb: add device tree support for r8a779[123]

Simply document new compatibility strings.
As a previous patch adds a generic R-Car Gen2 compatibility string
there appears to be no need for a driver updates.
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/renesas,ravb.txt

@@ -5,6 +5,9 @@ interface contains.
 
 Required properties:
 - compatible: "renesas,etheravb-r8a7790" if the device is a part of R8A7790 SoC.
+	      "renesas,etheravb-r8a7791" if the device is a part of R8A7791 SoC.
+	      "renesas,etheravb-r8a7792" if the device is a part of R8A7792 SoC.
+	      "renesas,etheravb-r8a7793" if the device is a part of R8A7793 SoC.
 	      "renesas,etheravb-r8a7794" if the device is a part of R8A7794 SoC.
 	      "renesas,etheravb-r8a7795" if the device is a part of R8A7795 SoC.
 	      "renesas,etheravb-rcar-gen2" for generic R-Car Gen 2 compatible interface.