fat_search_long() returns 0 on success, -ENOENT/ENOMEM on failure.
Change the function comment accordingly.

While at it, fix some trivial typos.
Signed-off-by: NRavishankar N <cyberax82@gmail.com>
Signed-off-by: NNamjae Jeon <linkinjeon@gmail.com>
Acked-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>