arm64/mpam: Supplement err tips in info/last_cmd_status

hulk inclusion
category: bugfix
bugzilla: 48265
CVE: NA

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

In many cases writing resctrl interface may return failure, but
err tips in info/last_cmd_status remain ok.
e.g.
    > echo 'L3:5=7fff' > schemata
      -bash: echo: write error: Invalid argument
    > cat info/last_cmd_status
      ok
    > cat ctrlmon
      1
    > echo 1 > ctrlmon
      -bash: echo: write error: No such file or directory
    > cat info/last_cmd_status
      ok
We add extra tips when goes to this branches.

Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>