crypto: hisilicon/zip - add comments for 'hisi_zip_sqe'

Some fields of 'hisi_zip_sqe' are unused, and some fields have misc
utilities. So add comments for used fields and make others unnamed.

Signed-off-by: Yang Shen <shenyang39@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>