arm64/mpam: resctrl: Move ctrlmon sysfile write/read function to mpam_ctrlmon.c

hulk inclusion
category: feature
feature: ARM MPAM support
bugzilla: 48265
CVE: NA

--------------------------------

Resctrl ctrlmon write/read functions should be moved to mpam_ctrlmon.c
to make code clear.

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: Zheng Zengkai <zhengzengkai@huawei.com>