dt-bindings: usb: renesas,usb-xhci: Document r8a774e1 support

Document r8a774e1 xhci support. The driver will use the fallback
compatible string "renesas,rcar-gen3-xhci", therefore no driver
change is needed.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Marian-Cristian Rotariu <marian-cristian.rotariu.rb@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20200828075019.541-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/renesas,usb-xhci.yaml

@@ -30,6 +30,7 @@ properties:
               - renesas,xhci-r8a774a1 # RZ/G2M
               - renesas,xhci-r8a774b1 # RZ/G2N
               - renesas,xhci-r8a774c0 # RZ/G2E
+              - renesas,xhci-r8a774e1 # RZ/G2H
               - renesas,xhci-r8a7795  # R-Car H3
               - renesas,xhci-r8a7796  # R-Car M3-W
               - renesas,xhci-r8a77961 # R-Car M3-W+