crypto: ccree - adapt ccree essiv support to kcapi

The ESSIV support in ccree was added before the kernel
generic support and using a slightly different API.

Brings the ccree essiv interface into compliance with
kernel crypto api one.

Since CryptoCell only support 256 bit AES key for ESSIV,
also use a fallback if requested a smaller key size.
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Libo Wang <libo.wang@arm.com>
Cc: Markus Elfring <Markus.Elfring@web.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>