crypto: hash - Add crypto_ahash_has_setkey

commit a5596d63 upstream.

This patch adds a way for ahash users to determine whether a key
is required by a crypto_ahash transform.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>