dt-bindings: usb: xhci-tegra: Add Tegra210 XUSB controller support

Extend the Tegra XUSB controller device tree binding with Tegra210
support.

Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>