PM / devfreq: Add HiSilicon uncore frequency scaling driver

PM / devfreq: Add HiSilicon uncore frequency scaling driver

Add the HiSilicon uncore frequency scaling driver for Kunpeng SoCs based on
the devfreq framework.  The uncore domain contains shared computing
resources, including system interconnects and L3 cache.  The uncore
frequency significantly impacts the system-wide performance as well as
power consumption.  This driver adds support for runtime management of
uncore frequency from kernel and userspace.  The main function includes
setting and getting frequencies, changing frequency scaling policies, and
querying the list of CPUs whose performance is significantly related to
this uncore frequency domain, etc.  The driver communicates with a platform
controller through an ACPI PCC mailbox to take the actual actions of
frequency scaling.

Co-developed-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Huisong Li <lihuisong@huawei.com>
Signed-off-by: Jie Zhan <zhanjie9@hisilicon.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://patchwork.kernel.org/project/linux-pm/patch/20250623143401.4095045-3-zhanjie9@hisilicon.com/