dt-bindings: misc: tegra186-misc: Add Tegra234 support

The MISC block found on Tegra234 is mostly similar to the one on
Tegra194 but supports slightly different register sets that make
it incompatible.

Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>