crypto: aegis128 - add support for SIMD acceleration

Add some plumbing to allow the AEGIS128 code to be built with SIMD
routines for acceleration.

Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>