mm, oom: fix a comment in dump_task()

If p is a kthread, it will be checked in oom_unkillable_task() so
we can delete the corresponding comment.

Link: https://lkml.kernel.org/r/20210125133006.7242-1-tangyizhou@huawei.com


Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>