arm64/mpam: resctrl: Re-synchronise resctrl's view of online CPUs

hulk inclusion
category: feature
bugzilla: 34278
CVE: NA

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So far we probe devices as they become accessible. Each time we probe
a new device, we eagerly schedule mpam_enable(). Once all the
devices have been probed mpam_enable() will poke resctrl.

At this point, resctrl has an inconcistent view of which CPUs are online,
as we only update the the classes that we picked, and we only
did that after there were enough CPUs online to have probed all
the devices.

Instead of having some complicated re-sync logic, unregister
the cpuhp callbacks, register resctrl, then re-register them.
As we know all the devices have been probed, no-one can find a new
one to cause mpam_enable() to be re-scheduled.

[Wang ShaoBo: many version adaptation changes]

Signed-off-by: James Morse <james.morse@arm.com>
Link: http://www.linux-arm.org/git?p=linux-jm.git;a=patch;h=e81ea2f3ca64d8e46a05195cb126a03f4ca846ef


Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Reviewed-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>