The top-level functions init/update/final were missing for ahash.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

All new crypto interfaces should go into individual files as much
as possible in order to ensure that crypto.h does not collapse under
its own weight.

This patch moves the ahash code into crypto/hash.h and crypto/internal/hash.h
respectively.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>