crypto: testmgr - constify all test vectors

Cryptographic test vectors should never be modified, so constify them to
enforce this at both compile-time and run-time.  This moves a significant
amount of data from .data to .rodata when the crypto tests are enabled.

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