dt-bindings: tegra: Add Tegra234 VDK compatible

The NVIDIA Tegra234 VDK is a simulation platform for the Orin SoC. It
supports a subset of the peripherals that will be available in the final
chip and serves as a bootstrapping platform.

Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>