dt-bindings: usb: renesas_usb3: add bindings for r8a77990

This patch adds bindings for r8a77990 (R-Car E3).
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_usb3.txt

@@ -6,6 +6,7 @@ Required properties:
 	- "renesas,r8a7795-usb3-peri"
 	- "renesas,r8a7796-usb3-peri"
 	- "renesas,r8a77965-usb3-peri"
+	- "renesas,r8a77990-usb3-peri"
 	- "renesas,rcar-gen3-usb3-peri" for a generic R-Car Gen3 or RZ/G2
 	  compatible device