regulator: core: Increase refcount for regulator supply's module

When a regulator is unregistered with regulator_unregister(), a call to
regulator_put() is made for its input supply if there is one. This does
a module_put() to decrement the refcount of the module that owns the
supply but there isn't a corresponding try_module_get() in set_supply()
to make the calls balanced.
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1105,6 +1105,9 @@ static int set_supply(struct regulator_dev *rdev,
 
 	rdev_info(rdev, "supplied by %s\n", rdev_get_name(supply_rdev));
 
+	if (!try_module_get(supply_rdev->owner))
+		return -ENODEV;
+
 	rdev->supply = create_regulator(supply_rdev, &rdev->dev, "SUPPLY");
 	if (rdev->supply == NULL) {
 		err = -ENOMEM;