ASoC: Support !REGULATOR build for sgtl5000

The regulator is optional depending on board design.

Signed-off-by: Mark Brown <[e-mail]>
Acked-by: Liam Girdwood <[e-mail]>

sound/soc/codecs/sgtl5000.c

···
 	return 0;
 }
 
+#ifdef CONFIG_REGULATOR
 static int ldo_regulator_is_enabled(struct regulator_dev *dev)
 {
 	struct ldo_regulator *ldo = rdev_get_drvdata(dev);
···
 
 	return 0;
 }
+#else
+static int ldo_regulator_register(struct snd_soc_codec *codec,
+				struct regulator_init_data *init_data,
+				int voltage)
+{
+	return -EINVAL;
+}
+
+static int ldo_regulator_remove(struct snd_soc_codec *codec)
+{
+	return 0;
+}
+#endif
 
 /*
  * set dac bias