Add Device Tree binding document for the Tegra234 DPAUX pin controller. Bug 3621816 Change-Id: Ie4920ce584e0a41c692fcf9f7f4035c3ab971559 Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/2704301 GVS: Gerrit_Virtual_Submit