crypto: aegis128 - drop empty TFM init/exit routines

TFM init/exit routines are optional, so no need to provide empty ones.

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>