headers_check fix: raid/md_p.h

fix the following 'make headers_check' warning:

  usr/include/linux/raid/md_p.h:85: 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/raid/md_p.h b/include/linux/raid/md_p.h
index 9491026..6ba830f 100644
--- a/include/linux/raid/md_p.h
+++ b/include/linux/raid/md_p.h
@@ -15,6 +15,8 @@
 #ifndef _MD_P_H
 #define _MD_P_H
 
+#include <linux/types.h>
+
 /*
  * RAID superblock.
  *