ASoC: Intel: Atom: platform-pcm: fix redundant return

Fix cppcheck warning

 return ret_val;
        ^
sound/soc/intel/atom/sst-mfld-platform-pcm.c:384:6: note: If condition 'ret_val' is true, the function will return/exit
 if (ret_val)
     ^
sound/soc/intel/atom/sst-mfld-platform-pcm.c:387:9: note: Returning identical expression 'ret_val'
 return ret_val;
        ^
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200813200147.61990-8-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/atom/sst-mfld-platform-pcm.c

@@ -385,7 +385,7 @@ static int sst_media_prepare(struct snd_pcm_substream *substream,
 	if (ret_val)
 		return ret_val;
 	substream->runtime->hw.info = SNDRV_PCM_INFO_BLOCK_TRANSFER;
-	return ret_val;
+	return 0;
 }
 
 static int sst_enable_ssp(struct snd_pcm_substream *substream,