doc: update docbook annotations for socket and skb

The skbuff and sock structure both had missing parameter annotation
values.
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -936,6 +936,7 @@ struct sk_buff_fclones {
 
 /**
  *	skb_fclone_busy - check if fclone is busy
+ *	@sk: socket
  *	@skb: buffer
  *
  * Returns true if skb is a fast clone, and its clone is not freed.

include/net/sock.h

@@ -252,6 +252,7 @@ struct sock_common {
   *	@sk_pacing_rate: Pacing rate (if supported by transport/packet scheduler)
   *	@sk_max_pacing_rate: Maximum pacing rate (%SO_MAX_PACING_RATE)
   *	@sk_sndbuf: size of send buffer in bytes
+  *	@sk_padding: unused element for alignment
   *	@sk_no_check_tx: %SO_NO_CHECK setting, set checksum in TX packets
   *	@sk_no_check_rx: allow zero checksum in RX packets
   *	@sk_route_caps: route capabilities (e.g. %NETIF_F_TSO)
@@ -302,6 +303,7 @@ struct sock_common {
   *	@sk_backlog_rcv: callback to process the backlog
   *	@sk_destruct: called at sock freeing time, i.e. when all refcnt == 0
   *	@sk_reuseport_cb: reuseport group container
+  *	@sk_rcu: used during RCU grace period
   */
 struct sock {
 	/*