sched: clear credit count in error branch

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7EBSH


CVE: NA

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Clear credit count if sched_prefer_cpus_fork failed.

Fixes: 243865da ("cpuset: Introduce new interface for scheduler dynamic affinity")
Signed-off-by: Hui Tang <tanghui20@huawei.com>
Reviewed-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Signed-off-by: Yipeng Zou <zouyipeng@huawei.com>