arm: tegra: dts: Support host/device selection and legacy mode

Some USB ports can support host and device operation. We add the dr_mode
property (as found in Freescale) for this.

One USB port has a 'legacy mode', left over from the days of pre-Tegra
chips. I don't believe this is actually used, except that we must know
to turn this off in the driver.
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

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

@@ -11,3 +11,16 @@ 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. Since this is a legacy issue it probably does not
+    warrant a compatible string of its own.