net: dsa: tag_rtl4_a: use the generic flow dissector procedure

Remove the .flow_dissect procedure, so the flow dissector will call the
generic variant which works for this tagging protocol.

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: DENG Qingfang <dqfext@gmail.com>
Cc: Mauri Sandberg <sandberg@mailfence.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/tag_rtl4_a.c

@@ -106,20 +106,11 @@ static struct sk_buff *rtl4a_tag_rcv(struct sk_buff *skb,
 	return skb;
 }
 
-static void rtl4a_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
-				   int *offset)
-{
-	*offset = RTL4_A_HDR_LEN;
-	/* Skip past the tag and fetch the encapsulated Ethertype */
-	*proto = ((__be16 *)skb->data)[1];
-}
-
 static const struct dsa_device_ops rtl4a_netdev_ops = {
 	.name	= "rtl4a",
 	.proto	= DSA_TAG_PROTO_RTL4_A,
 	.xmit	= rtl4a_tag_xmit,
 	.rcv	= rtl4a_tag_rcv,
-	.flow_dissect = rtl4a_tag_flow_dissect,
 	.overhead = RTL4_A_HDR_LEN,
 };
 module_dsa_tag_driver(rtl4a_netdev_ops);