drivers/crypto: fix session-less mode

drivers/crypto: fix session-less mode

When OpenSSL or AESNI-MB cryptodev is being used in sessionless mode
for symmetric crypto operation (e.g. SHA256 hash), the driver prints
error message:

    CRYPTODEV: set_sym_session_private_data() line 489:
               Set private data for driver 0 not allowed

Then, AESNI-MB driver segfaults in post_process_mb_job().

Bugzilla ID: 377
Fixes: b3bbd9e5f2 ("cryptodev: support device independent sessions")
Fixes: c68d7aa354 ("crypto/aesni_mb: use architecture independent macros")
Cc: stable@dpdk.org
Signed-off-by: Junxiao Shi <git@mail1.yoursunny.com>