dt-bindings: tegra: Add VI and CSI bindings

Tegra contains VI controller which can support up to 6 MIPI CSI
camera sensors.

Each Tegra CSI port from CSI unit can be one-to-one mapper to
VI channel and can capture from an external camera sensor or
from built-in test pattern generator.

This patch adds dt-bindings for Tegra VI and CSI.

Acked-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>