crypto: api - Do not wait for tests during registration

As registration is usually carried out during module init, this
is a context where as little work as possible should be carried
out.  Testing may trigger module loads of underlying components,
which could even lead back to the module that is registering at
the moment.  This may lead to dead-locks outside of the Crypto API.

Avoid this by not waiting for the tests to complete.  They will
be scheduled but completion will be asynchronous.  Any users will
still wait for completion.

Reported-by: Russell King <linux@armlinux.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>