crypto: testmgr - Test skciphers with no IVs

As it is an skcipher with no IV escapes testing altogether because
we only test givcipher objects.  This patch fixes the bypass logic
to test these algorithms.

Conversely, we're currently testing nivaead algorithms with IVs,
which would have deadlocked had it not been for the fact that no
nivaead algorithms have any test vectors.  This patch also fixes
that case.

Both fixes are ugly as hell, but this ugliness should hopefully
disappear once we move them into the per-type code (i.e., the
AEAD test would live in aead.c and the skcipher stuff in ablkcipher.c).

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>