crypto: n2 - Add Niagara2 crypto driver

Current deficiencies:

1) No HMAC hash support yet.

2) Although the algs are registered as ASYNC they always run
   synchronously.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>