test/crypto: change cipher offset for ESN vector

In the IPSEC ESN test vector the cipher offset for encryption
should be 8 bytes which is the size of esp header.
This patch also changes the ciphertext and the digest reference
data against which the operation result is validated.

Fixes: 699741912d71 ("test/crypto: add case for auth only trailer")
Cc: stable@dpdk.org
Signed-off-by: Ankur Dwivedi <adwivedi@marvell.com>
Acked-by: Akhil Goyal <akhil.goyal@nxp.com>