net_cls: remove duplicated include from cls_api.c

Remove duplicated include.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_api.c

@@ -22,7 +22,6 @@
 #include <linux/skbuff.h>
 #include <linux/init.h>
 #include <linux/kmod.h>
-#include <net/netlink.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <net/net_namespace.h>