Convert alg_test_skcipher() to use the new test framework, adding a list
of testvec_configs to test by default.  When the extra self-tests are
enabled, randomly generated testvec_configs are tested as well.

This improves skcipher test coverage mainly because now all algorithms
have a variety of data layouts tested, whereas before each algorithm was
responsible for declaring its own chunked test cases which were often
missing or provided poor test coverage.  The new code also tests both
the MAY_SLEEP and !MAY_SLEEP cases, different IV alignments, and buffers
that cross pages.

This has already found a bug in the arm64 ctr-aes-neonbs algorithm.
It would have easily found many past bugs.

I removed the skcipher chunked test vectors that were the same as
non-chunked ones, but left the ones that were unique.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>