crypto-openssl: refactor openssl API usage

crypto-openssl: refactor openssl API usage

For the openssl crypto engine based cipher encrypt/decrypt and HMAC IPSec
use cases, the openssl API calls of doing ctx init and key expansion are
moved to initialization stage.

In current implementation , the ctx is initialized with "key" and "iv" in
EVP_EncryptInit_ex (ctx, 0, 0, key->data, op->iv)
in data plane, while the ctx can be initialized with 'key' and 'iv' separately,
which means there could be two API calls:
 1. EVP_EncryptInit_ex (ctx, 0, 0, key->data, 0)
 2. EVP_EncryptInit_ex (ctx, 0, 0, 0, op->iv)

As the 'key' for certain IPSec SA is fixed and known, so call #1 can
be placed in IPSec SA initialization stage.
While call #2 should be kept in data plane for each packet, as the "iv"
is random for each packet.

Type: feature
Signed-off-by: Lijian Zhang <Lijian.Zhang@arm.com>
Change-Id: Ided4462c1d4a38addc3078b03d618209e040a07a