crypto: testmgr - Add infrastructure for ansi_cprng self-tests

Add some necessary infrastructure to make it possible to run
self-tests for ansi_cprng. The bits are likely very specific
to the ANSI X9.31 CPRNG in AES mode, and thus perhaps should
be named more specifically if/when we grow additional CPRNG
support...

Successfully tested against the cryptodev-2.6 tree and a
Red Hat Enterprise Linux 5.x kernel with the follow-on
patch that adds the actual test vectors.

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>