ACPI / PPTT: Add a helper to fill a cpumask from a processor container

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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The ACPI table for MPAM describes a set of CPUs with the UID of a
processor container. These exist both in the namespace and the PPTT.

Using the existing for-each helpers, provide a helper to find the
specified processor container in the PPTT, and fill a cpumask
with the CPUs that belong to it.

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