arm64: tegra: Add pin control states for I2C on Tegra186

Two of the Tegra I2C controllers share pads with the DPAUX controllers.
In order for the I2C controllers to use these pads, they have to be set
into I2C mode. Use the I2C and off pin control states defined in the DT
nodes for DPAUX as "default" and "idle" states, respectively. This
ensures that the I2C controller driver can properly configure the pins
when it needs to perform I2C transactions.

Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>