dt-bindings: display: renesas: du: Document the r8a77470 bindings

Document the RZ/G1C (r8a77470) SoC in R-Car DU bindings.
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Biju Das <biju.das@bp.renesas.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/renesas,du.txt

@@ -5,6 +5,7 @@ Required Properties:
   - compatible: must be one of the following.
     - "renesas,du-r8a7743" for R8A7743 (RZ/G1M) compatible DU
     - "renesas,du-r8a7745" for R8A7745 (RZ/G1E) compatible DU
+    - "renesas,du-r8a77470" for R8A77470 (RZ/G1C) compatible DU
     - "renesas,du-r8a7779" for R8A7779 (R-Car H1) compatible DU
     - "renesas,du-r8a7790" for R8A7790 (R-Car H2) compatible DU
     - "renesas,du-r8a7791" for R8A7791 (R-Car M2-W) compatible DU
@@ -53,6 +54,7 @@ corresponding to each DU output.
 -----------------------------------------------------------------------------
  R8A7743 (RZ/G1M)       DPAD 0         LVDS 0         -              -
  R8A7745 (RZ/G1E)       DPAD 0         DPAD 1         -              -
+ R8A77470 (RZ/G1C)      DPAD 0         DPAD 1         LVDS 0         -
  R8A7779 (R-Car H1)     DPAD 0         DPAD 1         -              -
  R8A7790 (R-Car H2)     DPAD 0         LVDS 0         LVDS 1         -
  R8A7791 (R-Car M2-W)   DPAD 0         LVDS 0         -              -