crypto: hisilicon/sec - Use int type to store negative error codes

Change the 'ret' variable in sec_hw_init() from u32 to int, as
it needs to store either negative error codes or zero returned by
sec_ipv4_hashmask().

No effect on runtime.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>