arm64: mpam: Add helpers to change a tasks and cpu mpam partid/pmg values

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8T2RT

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/log/?h=mpam/snapshot/v6.7-rc2



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Care must be taken when modifying the partid and pmg of a task, as
writing these values may race with the task being scheduled in, and
reading the modified values.

Add helpers to set the task properties, and the cpu default value,
and add the plumbing to the mpam driver that lets resctrl use them.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Zeng Heng <zengheng4@huawei.com>