fs/affs: remove node generation check

node generation has to be stored on disk.
AFAICS we won't be able to manage it on AFFS.
This patch removes relevant check in affs_nfs_get_inode()

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>