Remove silly and incorrect error message.

Commit 32133050 introduced a bug that gives a bogus error message on
every 'general' (non-event) PTP packet. If we want to catch missing
time stamps, then it has to occur at the port level.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>

udp.c

@@ -298,8 +298,6 @@ static int receive(int fd, void *buf, int buflen,
 
 	if (!ts) {
 		memset(&hwts->ts, 0, sizeof(hwts->ts));
-		if (cnt > 0)
-			pr_err("missing SO_TIMESTAMPING message");
 		return cnt;
 	}