tcp: Trivial fix to correct function name in a comment in net/ipv4/tcp.c

This is a trivial fix to correct function name in a comment in
net/ipv4/tcp.c.
Signed-off-by: NSatoru SATOH <satoru.satoh@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp.c

@@ -1722,7 +1722,7 @@ static int tcp_close_state(struct sock *sk)
 
 /*
  *	Shutdown the sending side of a connection. Much like close except
- *	that we don't receive shut down or set_sock_flag(sk, SOCK_DEAD).
+ *	that we don't receive shut down or sock_set_flag(sk, SOCK_DEAD).
  */
 
 void tcp_shutdown(struct sock *sk, int how)