arm64: zynqmp: Add maximum-speed property for dwc3 nodes

dwc3 can be used only for higher speeds than super-speed that's why
explicitly set it up.
This is also aligned with other ZynqMP dts files.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/arm/dts/zynqmp-zcu208-revA.dts b/arch/arm/dts/zynqmp-zcu208-revA.dts
index 03c84ae..7607098 100644
--- a/arch/arm/dts/zynqmp-zcu208-revA.dts
+++ b/arch/arm/dts/zynqmp-zcu208-revA.dts
@@ -701,4 +701,5 @@
 	snps,usb3_lpm_capable;
 	phy-names = "usb3-phy";
 	phys = <&psgtr 2 PHY_TYPE_USB3 0 2>;
+	maximum-speed = "super-speed";
 };