xfrm: Const'ify address arguments to xfrm_addr_cmp()

Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/xfrm.h

@@ -1520,7 +1520,8 @@ struct scatterlist;
 typedef int (icv_update_fn_t)(struct hash_desc *, struct scatterlist *,
 			      unsigned int);
 
-static inline int xfrm_addr_cmp(xfrm_address_t *a, xfrm_address_t *b,
+static inline int xfrm_addr_cmp(const xfrm_address_t *a,
+				const xfrm_address_t *b,
 				int family)
 {
 	switch (family) {