mm/damon/sysfs: return 'err' value when call kstrtoul() failed

mainline inclusion
from mainline-v6.2-rc6
commit 30b6242c
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6MRUG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=30b6242c49cd2a98def3bb2feee68d82a0e9686b

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We had better return the 'err' value when calling kstrtoul() failed, so
the user will know why it really fails, there do little change, let it
return the 'err' value when failed.

Link: https://lkml.kernel.org/r/6329ebe0.050a0220.ec4bd.297cSMTPIN_ADDED_BROKEN@mx.google.com


Suggested-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Xin Hao <xhao@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ze Zuo <zuoze1@huawei.com>