usb: host: max3421-hcd: Fix potential NULL urb dereference

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Mosberger <davidm@egauge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/max3421-hcd.c

@@ -588,12 +588,14 @@ max3421_next_transfer(struct usb_hcd *hcd, int fast_retransmit)
 {
 	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
 	struct urb *urb = max3421_hcd->curr_urb;
-	struct max3421_ep *max3421_ep = urb->ep->hcpriv;
+	struct max3421_ep *max3421_ep;
 	int cmd = -EINVAL;
 
 	if (!urb)
 		return;	/* nothing to do */
 
+	max3421_ep = urb->ep->hcpriv;
+
 	switch (max3421_ep->pkt_state) {
 	case PKT_STATE_SETUP:
 		cmd = max3421_ctrl_setup(hcd, urb);