fib: Use const struct nl_info * in rtmsg_fib

The rtmsg_fib function doesn't modify this argument so mark
it const.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/fib_lookup.h

@@ -32,7 +32,7 @@ extern int fib_dump_info(struct sk_buff *skb, u32 pid, u32 seq, int event,
 			 int dst_len, u8 tos, struct fib_info *fi,
 			 unsigned int);
 extern void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
-		      int dst_len, u32 tb_id, struct nl_info *info,
+		      int dst_len, u32 tb_id, const struct nl_info *info,
 		      unsigned int nlm_flags);
 extern struct fib_alias *fib_find_alias(struct list_head *fah,
 					u8 tos, u32 prio);

net/ipv4/fib_semantics.c

@@ -380,7 +380,7 @@ static inline size_t fib_nlmsg_size(struct fib_info *fi)
 }
 
 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
-	       int dst_len, u32 tb_id, struct nl_info *info,
+	       int dst_len, u32 tb_id, const struct nl_info *info,
 	       unsigned int nlm_flags)
 {
 	struct sk_buff *skb;