crypto: testmgr - Add a flag allowing the self-tests to be disabled at runtime.

Running self-tests for a short-lived KVM VM takes 28ms on my laptop.
This commit adds a flag 'cryptomgr.notests' which allows them to be
disabled.

However if fips=1 as well, we ignore this flag as FIPS mode mandates
that the self-tests are run.

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>