packet: propagate sock_cmsg_send() error

sock_cmsg_send() can return different error codes and not only
-EINVAL, and we should properly propagate them.

Fixes: c14ac9451c34 ("sock: enable timestamping using control messages")
Signed-off-by: Soheil Hassas Yeganeh <[e-mail]>
Cc: Willem de Bruijn <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/packet/af_packet.c

···
 	sockc.tsflags = sk->sk_tsflags;
 	if (msg->msg_controllen) {
 		err = sock_cmsg_send(sk, msg, &sockc);
-		if (unlikely(err)) {
-			err = -EINVAL;
+		if (unlikely(err))
 			goto out_unlock;
-		}
 	}
 
 	skb->protocol = proto;