[NET_SCHED]: mark classifier ops __read_mostly

Additionally remove unnecessary NULL initilizations of the next pointer.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index c390082..7bf3cd4 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -751,8 +751,7 @@
 	return -1;
 }
 
-static struct tcf_proto_ops cls_u32_ops = {
-	.next		=	NULL,
+static struct tcf_proto_ops cls_u32_ops __read_mostly = {
 	.kind		=	"u32",
 	.classify	=	u32_classify,
 	.init		=	u32_init,