[CRYPTO] xcbc: New algorithm

This is core code of XCBC.

XCBC is an algorithm that forms a MAC algorithm out of a cipher algorithm.
For example, AES-XCBC-MAC is a MAC algorithm based on the AES cipher
algorithm.

Signed-off-by: Kazunori MIYAZAWA <miyazawa@linux-ipv6.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>