[PATCH] fat: Fix truncate() write ordering

The truncate() should write the file size before writing the new EOF entry.
This patch fixes it.

This bug was pointed out by Machida Hiroyuki.

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>