net: skbuff: don't zero tc members when freeing skb

Not needed, only four cases:
- kfree_skb (or one of its aliases).
Don't need to zero, memory will be freed.
- kfree_skb_partial and head was stolen: memory will be freed.
- skb_morph: The skb header fields (including tc ones) will be
copied over from the 'to-be-morphed' skb right after
skb_release_head_state returns.
- skb_segment: Same as before, all the skb header
fields are copied over from the original skb right away.

Signed-off-by: Florian Westphal <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/core/skbuff.c

···
 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 	nf_bridge_put(skb->nf_bridge);
 #endif
-/* XXX: IS this still necessary? - JHS */
-#ifdef CONFIG_NET_SCHED
-	skb->tc_index = 0;
-#ifdef CONFIG_NET_CLS_ACT
-	skb->tc_verd = 0;
-#endif
-#endif
 }
 
 /* Free everything but the sk_buff shell. */