net: skb_flow_get_be16() can be static

Removes following sparse complain :

net/core/flow_dissector.c:70:8: warning: symbol 'skb_flow_get_be16'
was not declared. Should it be static?

Fixes: 972d3876 ("flow dissector: ICMP support")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/flow_dissector.c

@@ -67,8 +67,8 @@ EXPORT_SYMBOL(skb_flow_dissector_init);
  * The function will try to retrieve a be32 entity at
  * offset poff
  */
-__be16 skb_flow_get_be16(const struct sk_buff *skb, int poff, void *data,
-			 int hlen)
+static __be16 skb_flow_get_be16(const struct sk_buff *skb, int poff,
+				void *data, int hlen)
 {
 	__be16 *u, _u;