flow_dissector: add missing header includes

Signed-off-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/flow_dissector.h

 #ifndef _NET_FLOW_DISSECTOR_H
 #define _NET_FLOW_DISSECTOR_H
 
+#include <linux/types.h>
+#include <linux/skbuff.h>
+
 /**
  * struct flow_dissector_key_basic:
  * @thoff: Transport header offset