crypto: api - Add new template create function

crypto: api - Add new template create function

This patch introduces the template->create function intended
to replace the existing alloc function.  The intention is for
create to handle the registration directly, whereas currently
the caller of alloc has to handle the registration.

This allows type-specific code to be run prior to registration.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>