tegra: fdt: Add additional USB binding

This adds a property to indicate a port which can switch between host and device
mode.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>

doc/device-tree-bindings/usb/tegra-usb.txt

@@ -11,3 +11,15 @@ Required properties :
  - phy_type : Should be one of "ulpi" or "utmi".
  - nvidia,vbus-gpio : If present, specifies a gpio that needs to be
    activated for the bus to be powered.
+
+Optional properties:
+  - dr_mode : dual role mode. Indicates the working mode for
+    nvidia,tegra20-ehci compatible controllers.  Can be "host", "peripheral",
+    or "otg".  Default to "host" if not defined for backward compatibility.
+      host means this is a host controller
+      peripheral means it is device controller
+      otg means it can operate as either ("on the go")
+  - nvidia,has-legacy-mode : boolean indicates whether this controller can
+    operate in legacy mode (as APX 2500 / 2600). In legacy mode some
+    registers are accessed through the APB_MISC base address instead of
+    the USB controller.