regulator: Fix return code from regulator_disable_deferred()

schedule_delayed_work() returns a bool indicating if the work was already
queued when it succeeds so we need to squash a true down to zero.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/core.c

@@ -1599,13 +1599,18 @@ static void regulator_disable_work(struct work_struct *work)
 int regulator_disable_deferred(struct regulator *regulator, int ms)
 {
 	struct regulator_dev *rdev = regulator->rdev;
+	int ret;
 
 	mutex_lock(&rdev->mutex);
 	rdev->deferred_disables++;
 	mutex_unlock(&rdev->mutex);
 
-	return schedule_delayed_work(&rdev->disable_work,
+	ret = schedule_delayed_work(&rdev->disable_work,
 				    msecs_to_jiffies(ms));
+	if (ret < 0)
+		return ret;
+	else
+		return 0;
 }
 EXPORT_SYMBOL_GPL(regulator_disable_deferred);