svm: Add svm_set_user_mpam_en to enable/disable mpam for smmu

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I49RB2


CVE: NA

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The user_mpam_en configuration is used to enable/disable
mpam for SMMU. If user_mpam_en is set as true, the memory
requests across SMMU will carry the mpamid information,
otherwise the mpamid will not take effect.

Signed-off-by: Xingang Wang <wangxingang5@huawei.com>
Reviewed-by: Yingtai Xie <xieyingtai@huawei.com>
Reviewed-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>