crypto: arm/sha256 - move SHA-224/256 ASM/NEON implementation to base layer
This removes all the boilerplate from the existing implementation, and replaces it with calls into the base layer. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>