net: ipv4: Publish fib_nlmsg_size()

Publish fib_nlmsg_size() to allow it to be used later on from
fib_alias_hw_flags_set().

Remove the inline keyword since it shouldn't be used inside C files.
Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/fib_lookup.h

@@ -42,6 +42,7 @@ int fib_dump_info(struct sk_buff *skb, u32 pid, u32 seq, int event,
 		  const struct fib_rt_info *fri, unsigned int flags);
 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa, int dst_len,
 	       u32 tb_id, const struct nl_info *info, unsigned int nlm_flags);
+size_t fib_nlmsg_size(struct fib_info *fi);
 
 static inline void fib_result_assign(struct fib_result *res,
 				     struct fib_info *fi)

net/ipv4/fib_semantics.c

@@ -452,7 +452,7 @@ int ip_fib_check_default(__be32 gw, struct net_device *dev)
 	return -1;
 }
 
-static inline size_t fib_nlmsg_size(struct fib_info *fi)
+size_t fib_nlmsg_size(struct fib_info *fi)
 {
 	size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 			 + nla_total_size(4) /* RTA_TABLE */