dax: use correct dev_t value

The dev_t variable in devm_create_dax_dev() is used before it's
first set:

drivers/dax/dax.c: In function 'devm_create_dax_dev':
drivers/dax/dax.c:205:39: error: 'dev_t' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31),
                                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/dax/dax.c:688:8: note: 'dev_t' was declared here

This reorders the code to how it looks correct to me.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 3bc52c45 ("dax: define a unified inode/address_space for device-dax mappings")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dax/dax.c

@@ -598,6 +598,8 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
 		goto err_minor;
 	}
 
+	dev_t = MKDEV(MAJOR(dax_devt), minor);
+	dev = &dax_dev->dev;
 	dax_dev->inode = dax_inode_get(&dax_dev->cdev, dev_t);
 	if (!dax_dev->inode) {
 		rc = -ENOMEM;
@@ -605,8 +607,6 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
 	}
 
 	/* device_initialize() so cdev can reference kobj parent */
-	dev_t = MKDEV(MAJOR(dax_devt), minor);
-	dev = &dax_dev->dev;
 	device_initialize(dev);
 
 	cdev = &dax_dev->cdev;