crypto: hisilicon - Fix return value check in hisi_zip_acompress()

The return valude of add_comp_head() is int, but @head_size is size_t,
which is a unsigned type.

	size_t head_size;
	...
	if (head_size < 0)  // it will never work
		return -ENOMEM

Modify the type of @head_size to int, then change the type to size_t
when invoke hisi_zip_create_req() as a parameter.

Fixes: 62c455ca

 ("crypto: hisilicon - add HiSilicon ZIP accelerator support")
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Acked-by: Zhou Wang <wangzhou1@hisilicon.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>