ASoC: rt5682-i2c: Use devm_clk_get_optional for optional clock

The mclk clock is optional, but it's currently using devm_clk_get:
simplify the handling by using devm_clk_get_optional instead.
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20211026081030.422481-1-angelogioacchino.delregno@collabora.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/rt5682-i2c.c

@@ -280,14 +280,9 @@ static int rt5682_i2c_probe(struct i2c_client *i2c,
 
 #ifdef CONFIG_COMMON_CLK
 	/* Check if MCLK provided */
-	rt5682->mclk = devm_clk_get(&i2c->dev, "mclk");
-	if (IS_ERR(rt5682->mclk)) {
-		if (PTR_ERR(rt5682->mclk) != -ENOENT) {
-			ret = PTR_ERR(rt5682->mclk);
-			return ret;
-		}
-		rt5682->mclk = NULL;
-	}
+	rt5682->mclk = devm_clk_get_optional(&i2c->dev, "mclk");
+	if (IS_ERR(rt5682->mclk))
+		return PTR_ERR(rt5682->mclk);
 
 	/* Register CCF DAI clock control */
 	ret = rt5682_register_dai_clks(rt5682);