ASoC: ad1836: remove useless return

ASoC: ad1836: remove useless return

Cppcheck warning:

sound/soc/codecs/ad1836.c:311:9: warning: Identical condition and return expression 'ret', return value is always 0 [identicalConditionAfterEarlyExit]
 return ret;
        ^
sound/soc/codecs/ad1836.c:308:6: note: If condition 'ret' is true, the function will return/exit
 if (ret)
     ^
sound/soc/codecs/ad1836.c:311:9: note: Returning identical expression 'ret'
 return ret;
        ^

Likely copy/paste between adc and dac cases.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210312182246.5153-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>