crypto: tcrypt - Do not exit on success in fips mode

At present, the tcrypt module always exits with an -EAGAIN upon
successfully completing all the tests its been asked to run. In fips
mode, integrity checking is done by running all self-tests from the
initrd, and its much simpler to check the ret from modprobe for
success than to scrape dmesg and/or /proc/crypto. Simply stay
loaded, giving modprobe a retval of 0, if self-tests all pass and
we're in fips mode.

A side-effect of tracking success/failure for fips mode is that in
non-fips mode, self-test failures will return the actual failure
return codes, rather than always returning -EAGAIN, which seems more
correct anyway.

The tcrypt_test() portion of the patch is dependent on my earlier
pair of patches that skip non-fips algs in fips mode, at least to
achieve the fully intended behavior.

Nb: testing this patch against the cryptodev tree revealed a test
failure for sha384, which I have yet to look into...

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>