fs/adfs: add helper to get discrecord from map

Add a helper to get the disc record from the map, rather than open
coding this in adfs_fill_super().

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/adfs/dir_f.c

@@ -9,7 +9,6 @@
  *
  *  E and F format directory handling
  */
-#include <linux/buffer_head.h>
 #include "adfs.h"
 #include "dir_f.h"