af_packet: tone down the Tx-ring unsupported spew.

Trinity and other fuzzers can hit this WARN on far too easily,
resulting in a tainted kernel that hinders automated fuzzing.

Replace it with a rate-limited printk.
Signed-off-by: Dave Jones <davej@codemonkey.org.uk>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/packet/af_packet.c

@@ -4151,7 +4151,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 
 	/* Opening a Tx-ring is NOT supported in TPACKET_V3 */
 	if (!closing && tx_ring && (po->tp_version > TPACKET_V2)) {
-		WARN(1, "Tx-ring is not supported.\n");
+		net_warn_ratelimited("Tx-ring is not supported.\n");
 		goto out;
 	}