Due to the subreq pointer misuse the private context memory. The aead
soft crypto occasionally casues the OS panic as setting the 64K page.
Here is fix it.

Fixes: 6c46a329 ("crypto: hisilicon/sec - add fallback tfm...")
Signed-off-by: Kai Ye <yekai13@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>