net: hns3: refactor dump mac tnl status of debugfs

mainline inclusion
from mainline-master
commit 7b07ab06
category: feature
bugzilla: 173966
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7b07ab06e6b00b4421a4dfd732e98b359e0bad91



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Currently, the debugfs command for dump mac tnl status is
implemented by "echo xxxx > cmd", and record the information
in dmesg. It's unnecessary and heavy. To improve it, create
a single file "mac_tnl_status" for it, and query it by command
"cat mac_tnl_status", return the result to userspace, rather
than record in dmesg.

The display style is below:
$ cat mac_tnl_status
Recently generated mac tnl interruption:
[0111204.175437] status = 0x30
[0154120.329912] status = 0x30

Signed-off-by: Jiaran Zhang <zhangjiaran@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Yongxin Li <liyongxin1@huawei.com>
Signed-off-by: Junxin Chen <chenjunxin1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>