headers_check fix: linux/virtio_blk.h

fix the following 'make headers_check' warning:

  usr/include/linux/virtio_blk.h:21: 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/virtio_blk.h b/include/linux/virtio_blk.h
index c1aef85..94c56d2 100644
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -2,6 +2,7 @@
 #define _LINUX_VIRTIO_BLK_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_block */