ARM: dts: meson-axg: add USB nodes for S400

Add the correcly architectured USB Glue node for Meson AXG and the
S400 board in -u-boot.dtsi until support in upstream Linux then
backported.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/arch/arm/dts/meson-axg-s400-u-boot.dtsi b/arch/arm/dts/meson-axg-s400-u-boot.dtsi
index c46eb3f..2c4b06f 100644
--- a/arch/arm/dts/meson-axg-s400-u-boot.dtsi
+++ b/arch/arm/dts/meson-axg-s400-u-boot.dtsi
@@ -3,6 +3,8 @@
  * Copyright (c) 2017 Amlogic, Inc. All rights reserved.
  */
 
+#include "meson-axg-u-boot.dtsi"
+
 /* wifi module */
 &sd_emmc_b {
 	status = "disabled";
@@ -12,3 +14,13 @@
 &sd_emmc_c {
 	status = "okay";
 };
+
+&usb {
+	status = "okay";
+	dr_mode = "otg";
+	vbus-supply = <&usb_pwr>;
+};
+
+&usb2_phy1 {
+	phy-supply = <&vcc_5v>;
+};