dt-bindings: Add HTE bindings

Introduces HTE devicetree binding details for the HTE subsystem. It
includes examples for the consumers, binding details for the providers
and specific binding details for the Tegra194 based HTE providers.

Signed-off-by: Dipen Patel <dipenp@nvidia.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>