ARM: tegra: Add the EC i2c tunnel to tegra124-venice2

This adds the EC i2c tunnel (and devices under it) to the
tegra124-venice2 device tree.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Tested-by: Andrew Bresticker <abrestic@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>