drm/tegra: dpaux: Use the correct definition for pad modes

Some of definitions in the code changed the meaning, unfortunately one
place missed the change.

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