crypto: hisilicon/sec2 - fix some cleanup issues

This patch fixes following cleanup issues:
 - The return value of the function is
   inconsistent with the actual return type.
 - After the pointer type is directly converted
   to the `__le64` type, the program may crash
   or produce unexpected results.

Signed-off-by: Qi Tao <taoqi10@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>