ASoC: tegra20: spdif: Support system suspend

Support system suspend by enforcing runtime PM suspend/resume.
Now there is no doubt that h/w is indeed stopped during suspend
and that h/w state will be properly restored after resume.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20211204143725.31646-12-digetx@gmail.com


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