openvswitch: Move key_attr_size() to flow_netlink.h.

flow-netlink has netlink related code.

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
diff --git a/net/openvswitch/flow_netlink.h b/net/openvswitch/flow_netlink.h
index 6355b1d..4f03706 100644
--- a/net/openvswitch/flow_netlink.h
+++ b/net/openvswitch/flow_netlink.h
@@ -37,6 +37,8 @@
 
 #include "flow.h"
 
+size_t ovs_key_attr_size(void);
+
 void ovs_match_init(struct sw_flow_match *match,
 		    struct sw_flow_key *key, struct sw_flow_mask *mask);