Add "struct fat_slot_info" for updating data of the directory entries.

 1) Rename "struct vfat_slot_info" to "struct fat_slot_info"
 2) Add "de" and "bh" to fat_slot_info instead of using argument.
 3) Replace the "vfat_slot_info + de + bh" by new fat_slot_info
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>