regulator: fix use after free issue

This is caused by dereferencing 'rdev' after put_device() in
the _regulator_get()/_regulator_put() functions.
This patch just moves the put_device() down a bit to avoid the
issue.
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20191124145835.25999-1-wenyang@linux.alibaba.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1937,8 +1937,8 @@ struct regulator *_regulator_get(struct device *dev, const char *id,
 	regulator = create_regulator(rdev, dev, id);
 	if (regulator == NULL) {
 		regulator = ERR_PTR(-ENOMEM);
-		put_device(&rdev->dev);
 		module_put(rdev->owner);
+		put_device(&rdev->dev);
 		return regulator;
 	}
 
@@ -2059,13 +2059,13 @@ static void _regulator_put(struct regulator *regulator)
 
 	rdev->open_count--;
 	rdev->exclusive = 0;
-	put_device(&rdev->dev);
 	regulator_unlock(rdev);
 
 	kfree_const(regulator->supply_name);
 	kfree(regulator);
 
 	module_put(rdev->owner);
+	put_device(&rdev->dev);
 }
 
 /**