net: hns3: add debugfs support for tm priority and qset info

mainline inclusion
from mainline-v5.12-rc1
commit 04987ca1
category: feature
bugzilla: NA
CVE: NA

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

In order to query tm priority and qset for debugging, adds
debugfs files tm_priority and tm_qset in newly created tm
directory.

Unlike previous debugfs commands, these files just support
read ops, so they only support to use cat command to dump
their info.

The new tm file style is acccording to suggestion from
Jakub Kicinski's opinion as link https://lkml.org/lkml/2020/9/29/2101

.

Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Reviewed-by: Junxin Chen <chenjunxin1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>