headers_check fix: linux/rtnetlink.h

fix the following 'make headers_check' warning:

  usr/include/linux/rtnetlink.h:328: found __[us]{8,16,32,64} type without #include <linux/types.h>

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index e88f705..1e5f673 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -1,6 +1,7 @@
 #ifndef __LINUX_RTNETLINK_H
 #define __LINUX_RTNETLINK_H
 
+#include <linux/types.h>
 #include <linux/netlink.h>
 #include <linux/if_link.h>
 #include <linux/if_addr.h>