dmaengine: rcar-dmac: Document R8A774C0 bindings

Renesas' RZ/G2E (R8A774C0) SoC has DMA controllers compatible
with this driver, therefore document RZ/G2E specific bindings.
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/dma/renesas,rcar-dmac.txt

@@ -21,6 +21,7 @@ Required Properties:
 		- "renesas,dmac-r8a7745" (RZ/G1E)
 		- "renesas,dmac-r8a77470" (RZ/G1C)
 		- "renesas,dmac-r8a774a1" (RZ/G2M)
+		- "renesas,dmac-r8a774c0" (RZ/G2E)
 		- "renesas,dmac-r8a7790" (R-Car H2)
 		- "renesas,dmac-r8a7791" (R-Car M2-W)
 		- "renesas,dmac-r8a7792" (R-Car V2H)