[PATCH] fat: add fat_getattr()

This adds fat_getattr() for setting stat->blksize. (FAT uses the size
of cluster for proper I/O)

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>