mm/ksm: generalize ksm_process_profit

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8YMGX


CVE: NA

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The ksm_process_profit() was only used by procfs before, so it is built
under CONFIG_PROC_FS. Now memcg with ksm also call it, so delete the
CONFIG_PROC_FS compilation dependency to make it more general.

Fixes: 8bafb5ea ("memcg: support ksm merge any mode per cgroup")
Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>