fs/affs: use unsigned int for string lengths

- Some min() were used with different types.

- Create a new variable in __affs_hash_dentry() to process
  affs_check_name()/min() return

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>