drm/tegra: dpaux: Clean-up on probe failure

If the probing of the DPAUX fails, then clocks are left enabled and the
DPAUX reset de-asserted. Add code to perform the necessary clean-up on
probe failure by disabling clocks and asserting the reset.

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