crypto: api - Remove instance larval fulfilment

In order to allow testing to complete asynchronously after the
registration process, instance larvals need to complete prior
to having a test result.  Support this by redoing the lookup for
instance larvals after completion.   This should locate the pending
test larval and then repeat the wait on that (if it is still pending).

As the lookup is now repeated there is no longer any need to compute
the fulfilment status and all that code can be removed.

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