Fix cppcheck warning:

sound/soc/intel/atom/sst/sst_pvt.c:201:9: warning: Identical condition
and return expression 'retval', return value is always 0
[identicalConditionAfterEarlyExit]
 return retval;
        ^
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200813200147.61990-11-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>