regulator: Check for constraints before using them for name

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

drivers/regulator/core.c

@@ -232,7 +232,7 @@ static ssize_t regulator_name_show(struct device *dev,
 	struct regulator_dev *rdev = dev_get_drvdata(dev);
 	const char *name;
 
-	if (rdev->constraints->name)
+	if (rdev->constraints && rdev->constraints->name)
 		name = rdev->constraints->name;
 	else if (rdev->desc->name)
 		name = rdev->desc->name;