arm_mpam: resctrl: Update the rmid reallocation limit

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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resctrl's limbo code needs to be told when the data left in a cache is
small enough for the partid+pmg value to be re-allocated.

x86 uses the cache size divded by the number of rmid users the cache
may have. Do the same, but for the smallest cache, and with the
number of partid-and-pmg users.

Querying the cache size can't happen until after cacheinfo_sysfs_init()
has run, so mpam_resctrl_setup() must wait until then.

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