Revert "flow_dissector: Fix vlan header offset in __skb_flow_dissect"

hulk inclusion
category: bugfix
bugzilla: 16589
CVE: NA

-------------------------------------------------

This reverts commit 703f67f815bc382034f72a0ac8b2e35fcd37688b.
The patch has introduced a bug, revert it and use a new fix.

net/core/flow_dissector.c

@@ -785,10 +785,6 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 		    skb && skb_vlan_tag_present(skb)) {
 			proto = skb->protocol;
 		} else {
-			if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX &&
-			    nhoff > sizeof(*vlan))
-				nhoff -=  sizeof(*vlan);
-
 			vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan),
 						    data, hlen, &_vlan);
 			if (!vlan) {