net/sched: Set default of CONFIG_NET_TC_SKB_EXT to N

This a new feature, it is preferred that it defaults to N.
We will probe the feature support from userspace before actually using it.

Fixes: 95a7233c

 ('net: openvswitch: Set OvS recirc_id from tc chain index')
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>