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>

include/linux/raid/md_p.h

@@ -15,6 +15,8 @@
 #ifndef _MD_P_H
 #define _MD_P_H
 
+#include <linux/types.h>
+
 /*
  * RAID superblock.
  *