cdx: Unlock on error path in rescan_store()

We added locking to this function but these two error paths were
accidentally overlooked.

Fixes: f0af81683466 ("cdx: Introduce lock to protect controller ops")
Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Abhijit Gangurde <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/cdx/cdx.c

···
 		pd = of_find_device_by_node(np);
 		if (!pd) {
 			of_node_put(np);
-			return -EINVAL;
+			count = -EINVAL;
+			goto unlock;
 		}
 
 		cdx = platform_get_drvdata(pd);
···
 		put_device(&pd->dev);
 	}
 
+unlock:
 	mutex_unlock(&cdx_controller_lock);
 
 	return count;