FIPS 140-2 IG A.9 XTS key check.

Add a check that the two keys used for AES-XTS are different.

One test case uses the same key for both of the AES-XTS keys.  This causes
a failure under FIP 140-2 IG A.9.  Mark the test as returning a failure.

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7120)