net: make skb an optional parameter for__skb_flow_dissect()

Fixes: commit 690e36e726d00d2 (net: Allow raw buffers to be passed into the flow dissector)
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2 files changed