fs: fat: fix spelling typo of values

vaules -> values

Link: https://lkml.kernel.org/r/20210302034817.30384-1-dingsenjie@163.com
Signed-off-by: dingsenjie <dingsenjie@yulong.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>