ASoC: rt5514: mark PM functions as __maybe_unused

The new functions are only used when CONFIG_PM is enabled,
leading to a harmless warning:

sound/soc/codecs/rt5514-spi.c:474:12: error: 'rt5514_resume' defined but not used [-Werror=unused-function]
sound/soc/codecs/rt5514-spi.c:464:12: error: 'rt5514_suspend' defined but not used [-Werror=unused-function]

This marks them as __maybe_unused to make the build silent
again.

Fixes: 58f1c07d ("ASoC: rt5514: Voice wakeup support.")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/rt5514-spi.c

@@ -461,7 +461,7 @@ static int rt5514_spi_probe(struct spi_device *spi)
 	return 0;
 }
 
-static int rt5514_suspend(struct device *dev)
+static int __maybe_unused rt5514_suspend(struct device *dev)
 {
 	int irq = to_spi_device(dev)->irq;
 
@@ -471,7 +471,7 @@ static int rt5514_suspend(struct device *dev)
 	return 0;
 }
 
-static int rt5514_resume(struct device *dev)
+static int __maybe_unused rt5514_resume(struct device *dev)
 {
 	struct snd_soc_platform *platform = snd_soc_lookup_platform(dev);
 	struct rt5514_dsp *rt5514_dsp =