dt-bindings: usb-xhci: Document r8a7743 support

Document r8a7743 xhci support. The driver will use the fallback
compatible string "renesas,rcar-gen2-xhci", therefore no driver
change is needed.
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/usb-xhci.txt

@@ -7,12 +7,14 @@ Required properties:
     - "marvell,armada3700-xhci" for Armada 37xx SoCs
     - "marvell,armada-375-xhci" for Armada 375 SoCs
     - "marvell,armada-380-xhci" for Armada 38x SoCs
+    - "renesas,xhci-r8a7743" for r8a7743 SoC
     - "renesas,xhci-r8a7790" for r8a7790 SoC
     - "renesas,xhci-r8a7791" for r8a7791 SoC
     - "renesas,xhci-r8a7793" for r8a7793 SoC
     - "renesas,xhci-r8a7795" for r8a7795 SoC
     - "renesas,xhci-r8a7796" for r8a7796 SoC
-    - "renesas,rcar-gen2-xhci" for a generic R-Car Gen2 compatible device
+    - "renesas,rcar-gen2-xhci" for a generic R-Car Gen2 or RZ/G1 compatible
+      device
     - "renesas,rcar-gen3-xhci" for a generic R-Car Gen3 compatible device
     - "xhci-platform" (deprecated)