dt-bindings: usb: renesas_usbhs: add bindings for r8a77990

This patch adds bindings for r8a77990 (R-Car E3).

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

Documentation/devicetree/bindings/usb/renesas_usbhs.txt

@@ -13,6 +13,7 @@ Required properties:
 	- "renesas,usbhs-r8a7795" for r8a7795 (R-Car H3) compatible device
 	- "renesas,usbhs-r8a7796" for r8a7796 (R-Car M3-W) compatible device
 	- "renesas,usbhs-r8a77965" for r8a77965 (R-Car M3-N) compatible device
+	- "renesas,usbhs-r8a77990" for r8a77990 (R-Car E3) compatible device
 	- "renesas,usbhs-r8a77995" for r8a77995 (R-Car D3) compatible device
 	- "renesas,usbhs-r7s72100" for r7s72100 (RZ/A1) compatible device
 	- "renesas,rcar-gen2-usbhs" for R-Car Gen2 or RZ/G1 compatible devices