cryptd_alloc_ahash() will allocate a cryptd-ed ahash for specified
algorithm name. The new allocated one is guaranteed to be cryptd-ed
ahash, so the shash underlying can be gotten via cryptd_ahash_child().
Signed-off-by: NHuang Ying <ying.huang@intel.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>