net_sched: initialize net pointer inside tcf_exts_init()

For tcindex filter, it is too late to initialize the
net pointer in tcf_exts_validate(), as tcf_exts_get_net()
requires a non-NULL net pointer. We can just move its
initialization into tcf_exts_init(), which just requires
an additional parameter.

This makes the code in tcindex_alloc_perfect_hash()
prettier.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index 444d15a..f006af2 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -497,7 +497,7 @@
 	if (!f)
 		goto errout;
 
-	err = tcf_exts_init(&f->exts, TCA_ROUTE4_ACT, TCA_ROUTE4_POLICE);
+	err = tcf_exts_init(&f->exts, net, TCA_ROUTE4_ACT, TCA_ROUTE4_POLICE);
 	if (err < 0)
 		goto errout;