crypto: mcryptd - remove pointless wrapper functions

There is no need for ahash_mcryptd_{update,final,finup,digest}(); we
should just call crypto_ahash_*() directly.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>