dt-bindings: iommu: Add NVIDIA Tegra CMDQV support

dt-bindings: iommu: Add NVIDIA Tegra CMDQV support

The Command Queue Virtualization (CMDQV) hardware is part of the
SMMUv3 implementation on NVIDIA Tegra SoCs. It assists in
virtualizing the command queue for the SMMU.

Add a new device tree binding document for nvidia,tegra264-cmdqv.

Also update the arm,smmu-v3 binding to include an optional nvidia,cmdqv
property. This property is a phandle to the CMDQV device node, allowing
the SMMU driver to associate with its corresponding CMDQV instance.
Restrict this property usage to Nvidia Tegra264 only.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>