ASoC: mediatek: mt8195: fix return value

ASoC: mediatek: mt8195: fix return value

cppcheck reports the following warning:

sound/soc/mediatek/mt8195/mt8195-dai-etdm.c:1299:10: style: Variable
'ret' is assigned a value that is never used. [unreadVariable]
 int ret = 0;
         ^

The suggested change aligns the implementation of
mt8195_afe_disable_etdm() with mt8195_afe_enable_etdm() - same
negative return value upon error.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20211025185933.144327-8-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>