The stats code resurrected the unions from the early days of
kernel crypto.  This patch starts the process of moving them
out to the individual type structures as we do for everything
else.

In particular, add a report_stat function to cra_type and call
that from the stats code if available.  This allows us to move
the actual code over one-by-one.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>