[NET_SCHED]: Constify struct tcf_ext_map

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c
index ee60b2d..7a7bff5 100644
--- a/net/sched/cls_tcindex.c
+++ b/net/sched/cls_tcindex.c
@@ -55,7 +55,7 @@
 	int fall_through;	/* 0: only classify if explicit match */
 };
 
-static struct tcf_ext_map tcindex_ext_map = {
+static const struct tcf_ext_map tcindex_ext_map = {
 	.police = TCA_TCINDEX_POLICE,
 	.action = TCA_TCINDEX_ACT
 };