ASoC: tegra20: spdif: Use more resource-managed helpers

Use resource-managed helpers to make code cleaner. Driver's remove callback
isn't needed anymore since driver is completely resource-managed now.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20211204143725.31646-10-digetx@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>