net: hns3: refactor dump qos pri map of debugfs

mainline inclusion
from mainline-master
commit 28d3bada
category: feature
bugzilla: 173966
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=28d3bada7d42e324ee8558e6d22c3d768a87af7b



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Currently, user gets priority map by implementing debugfs command
"echo dump qos pri map > cmd", this command will dump info in dmesg.
It's unnecessary and heavy.

To optimize it, create a single file "qos_pri_map" in tm directory
and use cat command to get info. It will return info to userspace,
rather than record in dmesg.

The display style is below:
$ cat qos_pri_map
vlan_to_pri: 0
PRI    TC
0       0
1       1
2       2
3       3
4       0
5       1
6       2

Signed-off-by: Guangbin Huang <huangguangbin2@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>