ASoC: nau8825: remove useless assignment

cppcheck warning:

sound/soc/codecs/nau8825.c:2113:10: style: Variable 'ret' is assigned
a value that is never used. [unreadVariable]
 int ret = 0;
         ^
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210312182246.5153-16-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/nau8825.c

@@ -2111,7 +2111,7 @@ static int nau8825_set_pll(struct snd_soc_component *component, int pll_id, int
 
 static int nau8825_mclk_prepare(struct nau8825 *nau8825, unsigned int freq)
 {
-	int ret = 0;
+	int ret;
 
 	nau8825->mclk = devm_clk_get(nau8825->dev, "mclk");
 	if (IS_ERR(nau8825->mclk)) {