arm_mpam: resctrl: Pick a value for num_rmid

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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After the changes to resctrl to support MPAM, num_rmid is only used as a
value that is unfortunately exposed to user-space. For MPAM, this value
doesn't mean anything, and whatever value we do expose will be wrong
for some use cases.

User-space may expect it can use this value to know how many 'extra'
monitor groups it can create. e.g. on x86 if num_closid=4, num_rmid=8,
then a total of 4 monitor groups can be created. If num_rmid were 2,
then only 2 control groups could be created.
For MPAM the number of pmg is very likely to be smaller than the number
of partid, but this doesn't restrict the creation of control groups,
as each control group has its own pmg space.

Pick 1 if monitoring is supported.

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