crypto: testmgr - always print the actual skcipher driver name

When alg_test() is called from tcrypt.ko rather than from the algorithm
registration code, "driver" is actually the algorithm name, not the
driver name.  So it shouldn't be used in places where a driver name is
wanted, e.g. when reporting a test failure or when checking whether the
driver is the generic driver or not.

Fix this for the skcipher algorithm tests by getting the driver name
from the crypto_skcipher that actually got allocated.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>