net: annotate ->poll() instances

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 4e09398..a634327 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -387,7 +387,7 @@ bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
 void tcp_close(struct sock *sk, long timeout);
 void tcp_init_sock(struct sock *sk);
 void tcp_init_transfer(struct sock *sk, int bpf_op);
-unsigned int tcp_poll(struct file *file, struct socket *sock,
+__poll_t tcp_poll(struct file *file, struct socket *sock,
 		      struct poll_table_struct *wait);
 int tcp_getsockopt(struct sock *sk, int level, int optname,
 		   char __user *optval, int __user *optlen);