headers_check fix: linux/pkt_cls.h

fix the following 'make headers_check' warning:

  linux/pkt_cls.h:122: found __[us]{8,16,32,64} type without #include <linux/types.h>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>

include/linux/pkt_cls.h

 #ifndef __LINUX_PKT_CLS_H
 #define __LINUX_PKT_CLS_H
 
+#include <linux/types.h>
 #include <linux/pkt_sched.h>
 
 /* I think i could have done better macros ; for now this is stolen from