dt-bindings: display: renesas: du: Document the r8a77961 bindings

Document the R-Car M3-W+ (R8A77961) SoC in the R-Car DU bindings.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

Documentation/devicetree/bindings/display/renesas,du.txt

@@ -20,6 +20,7 @@ Required Properties:
     - "renesas,du-r8a7794" for R8A7794 (R-Car E2) compatible DU
     - "renesas,du-r8a7795" for R8A7795 (R-Car H3) compatible DU
     - "renesas,du-r8a7796" for R8A7796 (R-Car M3-W) compatible DU
+    - "renesas,du-r8a77961" for R8A77961 (R-Car M3-W+) compatible DU
     - "renesas,du-r8a77965" for R8A77965 (R-Car M3-N) compatible DU
     - "renesas,du-r8a77970" for R8A77970 (R-Car V3M) compatible DU
     - "renesas,du-r8a77980" for R8A77980 (R-Car V3H) compatible DU
@@ -87,6 +88,7 @@ corresponding to each DU output.
  R8A7794 (R-Car E2)     DPAD 0         DPAD 1         -              -
  R8A7795 (R-Car H3)     DPAD 0         HDMI 0         HDMI 1         LVDS 0
  R8A7796 (R-Car M3-W)   DPAD 0         HDMI 0         LVDS 0         -
+ R8A77961 (R-Car M3-W+) DPAD 0         HDMI 0         LVDS 0         -
  R8A77965 (R-Car M3-N)  DPAD 0         HDMI 0         LVDS 0         -
  R8A77970 (R-Car V3M)   DPAD 0         LVDS 0         -              -
  R8A77980 (R-Car V3H)   DPAD 0         LVDS 0         -              -