mm: oom: move memcg_print_bad_task() out of mem_cgroup_scan_tasks()

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6NYW4


CVE: NA

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

raw call flow:

oom_kill_process
  -> mem_cgroup_scan_tasks(.., .., message)
    -> memcg_print_bad_task(message, ..)

message is "const char*" type, and incorrectly cast to
"oom_control*" type in memcg_print_bad_task.

Fix it by moving memcg_print_bad_task out of mem_cgroup_scan_tasks
and call it in select_bad_process and dump_tasks. Furthermore,
use struct oom_control* directly and remove the useless parm `ret`.

Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Kang Chen <void0red@hust.edu.cn>
(cherry picked from commit 789038c7)