dt-bindings: display: renesas: lvds: Document R8A77970 bindings

Document the R-Car V3M (R8A77970) SoC in the R-Car LVDS bindings.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt

@@ -13,6 +13,7 @@ Required properties:
   - "renesas,r8a7793-lvds" for R8A7793 (R-Car M2-N) compatible LVDS encoders
   - "renesas,r8a7795-lvds" for R8A7795 (R-Car H3) compatible LVDS encoders
   - "renesas,r8a7796-lvds" for R8A7796 (R-Car M3-W) compatible LVDS encoders
+  - "renesas,r8a77970-lvds" for R8A77970 (R-Car V3M) compatible LVDS encoders
 
 - reg: Base address and length for the memory-mapped registers
 - clocks: A phandle + clock-specifier pair for the functional clock