crypto: inside-secure - Move static cipher alg & mode settings to init

ctx->alg and ctx->mode were set from safexcel_send_req through the
various safexcel_encrypt and _decrypt routines, but this makes little
sense as these are static per ciphersuite. So moved to _init instead,
in preparation of adding more ciphersuites.

Signed-off-by: Pascal van Leeuwen <pvanleeuwen@verimatrix.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>