ASoC: codecs: nau8825: Simplify mclk initialization

Most of clk_xxx() functions do check if provided clk-pointer is
non-NULL. These do not check if the pointer is an error-pointer.
Providing such to a clk_xxx() results in a panic.

By utilizing _optional() variant of devm_clk_get() the driver code is
both simplified and more robust. There is no need to remember about
IS_ERR(clk) checks each time mclk is accessed.

Reviewed-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://msgid.link/r/20240221152516.852353-3-cezary.rojewski@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/nau8825.c

@@ -2836,16 +2836,12 @@ static int nau8825_read_device_properties(struct device *dev,
 	if (nau8825->adc_delay < 125 || nau8825->adc_delay > 500)
 		dev_warn(dev, "Please set the suitable delay time!\n");
 
-	nau8825->mclk = devm_clk_get(dev, "mclk");
-	if (PTR_ERR(nau8825->mclk) == -EPROBE_DEFER) {
-		return -EPROBE_DEFER;
-	} else if (PTR_ERR(nau8825->mclk) == -ENOENT) {
+	nau8825->mclk = devm_clk_get_optional(dev, "mclk");
+	if (IS_ERR(nau8825->mclk))
+		return PTR_ERR(nau8825->mclk);
+	if (!nau8825->mclk)
 		/* The MCLK is managed externally or not used at all */
-		nau8825->mclk = NULL;
 		dev_info(dev, "No 'mclk' clock found, assume MCLK is managed externally");
-	} else if (IS_ERR(nau8825->mclk)) {
-		return -EINVAL;
-	}
 
 	return 0;
 }