crypto: n2 - use __devexit not __exit in n2_unregister_algs

fixes fedora sparc build failure, thanks to kylem for helping with debugging

Signed-off-by: Dennis Gilmore <dgilmore@redhat.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>