crypto: tcrypt - remove AES-XTS-192 speed tests

Remove xts(aes) speed tests with 2 x 192-bit keys, since implementations
adhering strictly to IEEE 1619-2007 standard cannot cope with key sizes
other than 2 x 128, 2 x 256 bits - i.e. AES-XTS-{128,256}:
[...]
tcrypt: test 5 (384 bit key, 16 byte blocks):
caam_jr 8020000.jr: key size mismatch
tcrypt: setkey() failed flags=200000
[...]

Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>