USB: serial: sierra: fix potential deadlock at close

The portdata spinlock can be taken in interrupt context (via
sierra_outdat_callback()).
Disable interrupts when taking the portdata spinlock when discarding
deferred URBs during close to prevent a possible deadlock.

Fixes: 014333f ("USB: sierra: fix urb and memory leak on disconnect")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[ johan: amend commit message and add fixes and stable tags ]
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/sierra.c

@@ -770,9 +770,9 @@ static void sierra_close(struct usb_serial_port *port)
 		kfree(urb->transfer_buffer);
 		usb_free_urb(urb);
 		usb_autopm_put_interface_async(serial->interface);
-		spin_lock(&portdata->lock);
+		spin_lock_irq(&portdata->lock);
 		portdata->outstanding_urbs--;
-		spin_unlock(&portdata->lock);
+		spin_unlock_irq(&portdata->lock);
 	}
 
 	sierra_stop_rx_urbs(port);