ASoC: qcom: lpass-platform: remove useless assignment

cppcheck warning:

sound/soc/qcom/lpass-platform.c:791:10: style: Variable 'ret' is
assigned a value that is never used. [unreadVariable]
 int ret = -EINVAL;
         ^

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20210218222916.89809-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
