isdn/gigaset: drop duplicate declaration

Function gigaset_skb_sent was declared twice, identically, in gigaset.h.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/gigaset/gigaset.h

@@ -751,9 +751,6 @@ void gigaset_stop(struct cardstate *cs);
 /* Tell common.c that the driver is being unloaded. */
 int gigaset_shutdown(struct cardstate *cs);
 
-/* Tell common.c that an skb has been sent. */
-void gigaset_skb_sent(struct bc_state *bcs, struct sk_buff *skb);
-
 /* Append event to the queue.
  * Returns NULL on failure or a pointer to the event on success.
  * ptr must be kmalloc()ed (and not be freed by the caller).