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.

diff --cc sound/soc/mediatek/mt8365/mt8365-afe-pcm.c
Simple merge

diff --cc sound/soc/mediatek/mt8365/mt8365-dai-i2s.c
Simple merge

diff --cc sound/soc/mediatek/mt8365/mt8365-reg.h
Simple merge