dmaengine: usb-dmac: Document R8A7799{0,5} bindings

Renesas R-Car D3 (R8A77995) and E3 (R8A77990) SoCs also have the R-Car
gen2/3 compatible DMA controllers, so document the SoC specific binding.
Signed-off-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
[uli: squashed]
Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

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

@@ -12,6 +12,8 @@ Required Properties:
 	  - "renesas,r8a7795-usb-dmac" (R-Car H3)
 	  - "renesas,r8a7796-usb-dmac" (R-Car M3-W)
 	  - "renesas,r8a77965-usb-dmac" (R-Car M3-N)
+	  - "renesas,r8a77990-usb-dmac" (R-Car E3)
+	  - "renesas,r8a77995-usb-dmac" (R-Car D3)
 - reg: base address and length of the registers block for the DMAC
 - interrupts: interrupt specifiers for the DMAC, one for each entry in
   interrupt-names.