dt-bindings: memory: Add Tegra234 MGBE memory clients

Add the memory client and stream ID definitions for the MGBE hardware
found on Tegra234 SoCs.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Bhadram Varka <vbhadram@nvidia.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>