dt-bindings: display: renesas: du: Document the r8a774a1 bindings

Document the RZ/G2M (R8A774A1) SoC in the R-Car DU bindings.
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
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

@@ -7,6 +7,7 @@ Required Properties:
     - "renesas,du-r8a7744" for R8A7744 (RZ/G1N) compatible DU
     - "renesas,du-r8a7745" for R8A7745 (RZ/G1E) compatible DU
     - "renesas,du-r8a77470" for R8A77470 (RZ/G1C) compatible DU
+    - "renesas,du-r8a774a1" for R8A774A1 (RZ/G2M) compatible DU
     - "renesas,du-r8a774c0" for R8A774C0 (RZ/G2E) compatible DU
     - "renesas,du-r8a7779" for R8A7779 (R-Car H1) compatible DU
     - "renesas,du-r8a7790" for R8A7790 (R-Car H2) compatible DU
@@ -58,6 +59,7 @@ corresponding to each DU output.
  R8A7744 (RZ/G1N)       DPAD 0         LVDS 0         -              -
  R8A7745 (RZ/G1E)       DPAD 0         DPAD 1         -              -
  R8A77470 (RZ/G1C)      DPAD 0         DPAD 1         LVDS 0         -
+ R8A774A1 (RZ/G2M)      DPAD 0         HDMI 0         LVDS 0         -
  R8A774C0 (RZ/G2E)      DPAD 0         LVDS 0         LVDS 1         -
  R8A7779 (R-Car H1)     DPAD 0         DPAD 1         -              -
  R8A7790 (R-Car H2)     DPAD 0         LVDS 0         LVDS 1         -