share_pool: Free newly generated id when failed

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


CVE: NA

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Free id at the end of sp_group_add_task when failed.
Benefits are below:
1. Less time to hold locks.
2. Avoid to forget freeing id in other error handling branches.

Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Reviewed-by: Ding Tianhong <dingtianhong@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>