fs/affs/file.c: remove unnecessary function parameters

- affs_do_readpage_ofs is always called with from = 0 ie reading from
  page->index

- File parameter is never used

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>