crypto: hisilicon/zip - fix zero length input in GZIP decompress

The zero length input will cause a call trace when use GZIP
decompress like this:
    Unable to handle kernel paging request at virtual address
    ...
    lr : get_gzip_head_size+0x7c/0xd0 [hisi_zip]

Judge the input length and return '-EINVAL' when input is invalid.

Fixes: 62c455ca("crypto: hisilicon - add HiSilicon ZIP...")
Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
Signed-off-by: Yang Shen <shenyang39@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>