share_pool: Free spg_node when group adding failed

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4EUVI


CVE: NA

-------------------------------------------------

If group adding failed, we should release the memory of newly allocated
spg_node. sp_group_master and sp_proc_stat don't need to be freed as
they are released when process exits.

In addition, sp_proc_stat may not be initialized when group adding is
failed. Check this in sp_group_post_exit.

Also adjust the position of access control permission check.

Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>
Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Reviewed-by: Ding Tianhong <dingtianhong@huawei.com&gt;dd>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>