net: decnet: kerneldoc fixes

Simple fixes which require no deep knowledge of the code.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/decnet/dn_route.c

@@ -494,6 +494,8 @@ static int dn_return_long(struct sk_buff *skb)
 
 /**
  * dn_route_rx_packet - Try and find a route for an incoming packet
+ * @net: The applicable net namespace
+ * @sk: Socket packet transmitted on
  * @skb: The packet to find a route for
  *
  * Returns: result of input function if route is found, error code otherwise