[PATCH] fat: Replace an own implementation with ll_rw_block(SWRITE,)

This patch replaces an own implementation with LL_RW_BLOCK(SWRITE,) which was
newly added.

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>