crypto: atmel-aes - make crypto request queue management more generic

This patch changes atmel_aes_handle_queue() to make it more generic.
The function argument is now a pointer to struct crypto_async_request,
which is the common base of struct ablkcipher_request and
struct aead_request.

Also this patch introduces struct atmel_aes_base_ctx which will be the
common base of all the transformation contexts.

Hence the very same queue will be used to manage both block cipher and
AEAD requests (such as gcm and authenc implemented in further patches).

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>