ASoC: mt8365: Fix -Werror builds

ASoC: mt8365: Fix -Werror builds

Merge series from Mark Brown <broonie@kernel.org>:

Nathan reported that the newly added mt8365 drivers were causing a
number of warnings which break -Werror builds, these were only visible
on arm64 since the drivers did not have COMPILE_TEST enabled.  Fix this
and some other minor stuff I noticed while doing so.