arm64: tegra: Audio graph header for Tegra210

Expose a header which describes DT bindings required to use audio-graph
based sound card. All Tegra210 based platforms can include this header
and add platform specific information. Currently, from SoC point of view,
all links are exposed for ADMAIF, AHUB, I2S and DMIC components.

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