netfilter: fix Kconfig dependencies

Fix dependencies of netfilter realm match: it depends on NET_CLS_ROUTE,
which itself depends on NET_SCHED; this dependency is missing from netfilter.

Since matching on realms is also useful without having NET_SCHED enabled and
the option really only controls whether the tclassid member is included in
route and dst entries, rename the config option to IP_ROUTE_CLASSID and move
it outside of traffic scheduling context to get rid of the NET_SCHED dependeny.

Reported-by: Vladis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
index 5b271a1..a3b293d 100644
--- a/net/sched/cls_flow.c
+++ b/net/sched/cls_flow.c
@@ -276,7 +276,7 @@
 
 static u32 flow_get_rtclassid(const struct sk_buff *skb)
 {
-#ifdef CONFIG_NET_CLS_ROUTE
+#ifdef CONFIG_IP_ROUTE_CLASSID
 	if (skb_dst(skb))
 		return skb_dst(skb)->tclassid;
 #endif