dt-bindings: usb: xhci-tegra: Add Tegra186 support

Extend the bindings to cover the set of features found in Tegra186.

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: JC Kuo <jckuo@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>