dt-bindings: Add Host1x context stream IDs on Tegra234

Add defines for stream IDs used for Host1x context isolation
on Tegra234. The same stream IDs are used for both NISO0 and
NISO1 SMMUs since Host1x's stream ID protection tables don't
make a distinction between the two.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>