USB stv680, remove urb->next usage

Removed the use of the next field due to the change in the urb structure.

drivers/usb/media/stv680.c

@@ -799,7 +799,6 @@ static int stv680_stop_stream (struct usb_stv *stv680)
 
 	for (i = 0; i < STV680_NUMSBUF; i++)
 		if (stv680->urb[i]) {
-			stv680->urb[i]->next = NULL;
 			usb_unlink_urb (stv680->urb[i]);
 			usb_free_urb (stv680->urb[i]);
 			stv680->urb[i] = NULL;
@@ -1516,7 +1515,6 @@ static inline void usb_stv680_remove_disconnected (struct usb_stv *stv680)
 
 	for (i = 0; i < STV680_NUMSBUF; i++)
 		if (stv680->urb[i]) {
-			stv680->urb[i]->next = NULL;
 			usb_unlink_urb (stv680->urb[i]);
 			usb_free_urb (stv680->urb[i]);
 			stv680->urb[i] = NULL;