net: dsa: Drop WARN() in tag_brcm.c

We may be able to see invalid Broadcom tags when the hardware and drivers are
misconfigured, or just while exercising the error path. Instead of flooding
the console with messages, flat out drop the packet.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/tag_brcm.c

@@ -121,7 +121,8 @@ static int brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 	/* We should never see a reserved reason code without knowing how to
 	 * handle it
 	 */
-	WARN_ON(brcm_tag[2] & BRCM_EG_RC_RSVD);
+	if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
+		goto out_drop;
 
 	/* Locate which port this is coming from */
 	source_port = brcm_tag[3] & BRCM_EG_PID_MASK;