net: use WARN() for the WARN_ON in commit b6b39e8

Commit b6b39e8 (tcp: Try to catch MSG_PEEK bug) added a printk()
to the WARN_ON() that's in tcp.c. This patch changes this combination
to WARN(); the advantage of WARN() is that the printk message shows up
inside the message, so that kerneloops.org will collect the message.

In addition, this gets rid of an extra if() statement.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp.c

@@ -1442,9 +1442,9 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 				goto found_ok_skb;
 			if (tcp_hdr(skb)->fin)
 				goto found_fin_ok;
-			if (WARN_ON(!(flags & MSG_PEEK)))
-				printk(KERN_INFO "recvmsg bug 2: copied %X "
-				       "seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
+			WARN(!(flags & MSG_PEEK), KERN_INFO "recvmsg bug 2: "
+					"copied %X seq %X\n", *seq,
+					TCP_SKB_CB(skb)->seq);
 		}
 
 		/* Well, if we have backlog, try to process it now yet. */