ASoC: generic: simple-card-utils: remove useless assignment

cppcheck warning:

sound/soc/generic/simple-card-utils.c:258:10: 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/20210218221921.88991-7-pierre-louis.bossart@linux.intel.com


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