[CRYPTO] Add support for low-level multi-block operations

This patch adds hooks for cipher algorithms to implement multi-block
ECB/CBC operations directly.  This is expected to provide significant
performance boots to the VIA Padlock.

It could also be used for improving software implementations such as
AES where operating on multiple blocks at a time may enable certain
optimisations.

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