Add support for Advanced Encryption Standard (AES) in Counter Mode (CTR)
as provided in IPsec implementation standard RFC3686.

ablkcipher shared descriptors now save context registers after job
execution. This is used to load Nonce specific to RFC3686 only at
first execution of shared job descriptor.
Signed-off-by: Catalin Vasile <catalin.vasile@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>