[NET]: kernel-doc fix for sock.h

Fix kernel-doc warning in include/net/sock.h:
Warning(/var/linsrc/linux-2619-rc1-pv//include/net/sock.h:894): No description found for parameter 'rcu'
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -884,8 +884,7 @@ static inline int sk_filter(struct sock *sk, struct sk_buff *skb)
 
 /**
  *	sk_filter_release: Release a socket filter
- *	@sk: socket
- *	@fp: filter to remove
+ *	@rcu: rcu_head that contains the sk_filter info to remove
  *
  *	Remove a filter from a socket and release its resources.
  */