USB: serial: io_edgeport: fix use after free in debug printk

The "dev_dbg(&urb->dev->dev, ..." which happens after usb_free_urb(urb)
is a use after free of the "urb" pointer.  Store the "dev" pointer at the
start of the function to avoid this issue.

Fixes: 984f686 ("USB: serial: io_edgeport.c: remove dbg() usage")
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

Author: Dan Carpenter

drivers/usb/serial/io_edgeport.c

@@ -770,11 +770,12 @@ static void edge_bulk_out_data_callback(struct urb *urb)
 static void edge_bulk_out_cmd_callback(struct urb *urb)
 {
 	struct edgeport_port *edge_port = urb->context;
+	struct device *dev = &urb->dev->dev;
 	int status = urb->status;
 
 	atomic_dec(&CmdUrbs);
-	dev_dbg(&urb->dev->dev, "%s - FREE URB %p (outstanding %d)\n",
-		__func__, urb, atomic_read(&CmdUrbs));
+	dev_dbg(dev, "%s - FREE URB %p (outstanding %d)\n", __func__, urb,
+		atomic_read(&CmdUrbs));
 
 
 	/* clean up the transfer buffer */
@@ -784,8 +785,7 @@ static void edge_bulk_out_cmd_callback(struct urb *urb)
 	usb_free_urb(urb);
 
 	if (status) {
-		dev_dbg(&urb->dev->dev,
-			"%s - nonzero write bulk status received: %d\n",
+		dev_dbg(dev, "%s - nonzero write bulk status received: %d\n",
 			__func__, status);
 		return;
 	}