dt-bindings: Add bindings for Tegra234 NVDEC

Update NVDEC bindings for Tegra234. This new engine version only has
two memory clients, but now requires three clocks, and as a bigger
change the engine loads firmware from a secure carveout configured by
the bootloader.

For the latter, we need to add a phandle to the memory controller
to query the location of this carveout, and several other properties
containing offsets into the firmware inside the carveout. This
carveout is not accessible by the CPU, but is needed by NVDEC,
so we need this information to be relayed from the bootloader.

As the binding was getting large with many conditional properties,
also split the Tegra234 version out into a separate file.

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