ipv4: Fix fib_info->fib_metrics leak

Commit 4670994d(net,rcu: convert call_rcu(fc_rport_free_rcu) to
kfree_rcu()) introduced a memory leak. This patch reverts it.
Signed-off-by: NZheng Yan <zheng.z.yan@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/fib_semantics.c

@@ -142,6 +142,14 @@ const struct fib_prop fib_props[RTN_MAX + 1] = {
 };
 
 /* Release a nexthop info record */
+static void free_fib_info_rcu(struct rcu_head *head)
+{
+	struct fib_info *fi = container_of(head, struct fib_info, rcu);
+
+	if (fi->fib_metrics != (u32 *) dst_default_metrics)
+		kfree(fi->fib_metrics);
+	kfree(fi);
+}
 
 void free_fib_info(struct fib_info *fi)
 {
@@ -156,7 +164,7 @@ void free_fib_info(struct fib_info *fi)
 	} endfor_nexthops(fi);
 	fib_info_cnt--;
 	release_net(fi->fib_net);
-	kfree_rcu(fi, rcu);
+	call_rcu(&fi->rcu, free_fib_info_rcu);
 }
 
 void fib_release_info(struct fib_info *fi)