Add Device Tree binding document for the NVIDIA Tegra watchdog timer. Bug 3583627 Change-Id: I242585c8a543d03e0c58bfb9098fdbd1c780886e Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/2702336 GVS: Gerrit_Virtual_Submit