ASoC: mt6359-accdet.c: remove useless assignments

ASoC: mt6359-accdet.c: remove useless assignments

cppcheck warnings (and additional issue found by code inspection)

sound/soc/codecs/mt6359-accdet.c:464:10: style: Variable 'ret' is
assigned a value that is never used. [unreadVariable]
 int ret = 0;
         ^

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210804192456.278702-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>