ASoC: nau8825: mark pm functions __maybe_unused

The newly added nau8825_dai_is_active() function is only called from
the PM logic that is build-time conditional in this driver, so we get
a warning when CONFIG_PM is disabled:

sound/soc/codecs/nau8825.c:229:13: error: 'nau8825_dai_is_active' defined but not used [-Werror=unused-function]
 static bool nau8825_dai_is_active(struct nau8825 *nau8825)

By replacing the #ifdef around the functions with a __maybe_unused
annotation, the code becomes more robust to this kind of problem
and we no longer get the warning while also slightly improving
readability.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: b50455fa ("ASoC: nau8825: cross talk suppression measurement function")
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/nau8825.c

@@ -2216,8 +2216,7 @@ static int nau8825_set_bias_level(struct snd_soc_codec *codec,
 	return 0;
 }
 
-#ifdef CONFIG_PM
-static int nau8825_suspend(struct snd_soc_codec *codec)
+static int __maybe_unused nau8825_suspend(struct snd_soc_codec *codec)
 {
 	struct nau8825 *nau8825 = snd_soc_codec_get_drvdata(codec);
 
@@ -2229,7 +2228,7 @@ static int nau8825_suspend(struct snd_soc_codec *codec)
 	return 0;
 }
 
-static int nau8825_resume(struct snd_soc_codec *codec)
+static int __maybe_unused nau8825_resume(struct snd_soc_codec *codec)
 {
 	struct nau8825 *nau8825 = snd_soc_codec_get_drvdata(codec);
 
@@ -2253,10 +2252,6 @@ static int nau8825_resume(struct snd_soc_codec *codec)
 
 	return 0;
 }
-#else
-#define nau8825_suspend NULL
-#define nau8825_resume NULL
-#endif
 
 static struct snd_soc_codec_driver nau8825_codec_driver = {
 	.probe = nau8825_codec_probe,