crypto: sahara - remove 'active' flag from sahara_aes_reqctx struct

The 'active' flag is only used to indirectly set the 'first' flag.
Drop the 'active' flag and set 'first' directly in sahara_sha_init().

Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>