headers_check fix: linux/virtio_net.h

fix the following 'make headers_check' warning:

  usr/include/linux/virtio_net.h:28: found __[us]{8,16,32,64} type without #include <linux/types.h>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>

include/linux/virtio_net.h

@@ -2,6 +2,7 @@
 #define _LINUX_VIRTIO_NET_H
 /* This header is BSD licensed so anyone can use the definitions to implement
  * compatible drivers/servers. */
+#include <linux/types.h>
 #include <linux/virtio_config.h>
 
 /* The ID for virtio_net */