headers_check fix: linux/pkt_sched.h

fix the following 'make headers_check' warning:

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

include/linux/pkt_sched.h

 #ifndef __LINUX_PKT_SCHED_H
 #define __LINUX_PKT_SCHED_H
 
+#include <linux/types.h>
+
 /* Logical priority bands not depending on specific packet scheduler.
    Every scheduler will map them to real traffic classes, if it has
    no more precise mechanism to classify packets.