crypto: hisilicon - fix param should be static when not external.

This patch fixes following sparse warning:
zip_main.c:87:1: warning: symbol 'hisi_zip_list' was not declared.
Should it be static?
zip_main.c:88:1: warning: symbol 'hisi_zip_list_lock' was not declared.
Should it be static?
zip_main.c:948:68: warning: Using plain integer as NULL pointer

Signed-off-by: Shukun Tan <tanshukun1@huawei.com>
Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>