arm64/mpam: fix the problem that the ret variable is not initialized

kylin inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4AHUL


CVE: NA

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initialize the value "ret" in "schemata_list_init()"

Signed-off-by: wenzhiwei11 <wenzhiwei@kylinos.cn> # openEuler_contributor
Reviewed-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>