net/core: Document __skb_flow_dissect() flags argument

This patch avoids that the following warning is reported when building
with W=1:

warning: Function parameter or member 'flags' not described in '__skb_flow_dissect'

Cc: Tom Herbert <tom@herbertland.com>
Fixes: cd79a238 ("flow_dissector: Add flags argument to skb_flow_dissector functions") # v4.3.
Signed-off-by: NBart Van Assche <bvanassche@acm.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/flow_dissector.c

@@ -732,6 +732,8 @@ bool __skb_flow_bpf_dissect(struct bpf_prog *prog,
  * @proto: protocol for which to get the flow, if @data is NULL use skb->protocol
  * @nhoff: network header offset, if @data is NULL use skb_network_offset(skb)
  * @hlen: packet header length, if @data is NULL use skb_headlen(skb)
+ * @flags: flags that control the dissection process, e.g.
+ *         FLOW_DISSECTOR_F_STOP_AT_L3.
  *
  * The function will try to retrieve individual keys into target specified
  * by flow_dissector from either the skbuff or a raw buffer specified by the