crypto: hash - add crypto_(un)register_ahashes()

There are already helpers to (un)register multiple normal
and AEAD algos.  Add one for ahashes too.

Signed-off-by: Lars Persson <larper@axis.com>
Signed-off-by: Rabin Vincent <rabinv@axis.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>