The hisi_acc_create_sgl_pool() function returns error pointers, it never
returns NULL pointers.

Fixes: 416d8220 ("crypto: hisilicon - add HiSilicon SEC V2 driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>