crypto: hisilicon/qm - fix wrong release after using strsep

Save the string address before pass to strsep, release it at end.
Because strsep will update the string address to point after the
token.

Fixes: c31dc9fe

("crypto: hisilicon/qm - add DebugFS for xQC and...")
Signed-off-by: Sihang Chen <chensihang1@hisilicon.com>
Signed-off-by: Yang Shen <shenyang39@huawei.com>
Reviewed-by: Zhou Wang <wangzhou1@hisilicon.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>