Fix cppcheck warning:

[sound/soc/intel/boards/kbl_rt5663_rt5514_max98927.c:764]: (style)
Variable 'ret' is assigned a value that is never used.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200113210428.27457-13-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>