net: flow: Remove unused inline function

It is not used since commit 09c75704 ("xfrm: remove flow cache")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/flow.h

@@ -204,24 +204,6 @@ static inline struct flowi *flowidn_to_flowi(struct flowidn *fldn)
 	return container_of(fldn, struct flowi, u.dn);
 }
 
-typedef unsigned long flow_compare_t;
-
-static inline unsigned int flow_key_size(u16 family)
-{
-	switch (family) {
-	case AF_INET:
-		BUILD_BUG_ON(sizeof(struct flowi4) % sizeof(flow_compare_t));
-		return sizeof(struct flowi4) / sizeof(flow_compare_t);
-	case AF_INET6:
-		BUILD_BUG_ON(sizeof(struct flowi6) % sizeof(flow_compare_t));
-		return sizeof(struct flowi6) / sizeof(flow_compare_t);
-	case AF_DECnet:
-		BUILD_BUG_ON(sizeof(struct flowidn) % sizeof(flow_compare_t));
-		return sizeof(struct flowidn) / sizeof(flow_compare_t);
-	}
-	return 0;
-}
-
 __u32 __get_hash_from_flowi6(const struct flowi6 *fl6, struct flow_keys *keys);
 
 #endif