net: hns3: refactor dump tc of debugfs

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

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

The display style is below:
$ cat tc_sch_info
enabled tc number: 4
weight_offset: 14
TC    MODE  WEIGHT
0     dwrr     25
1     dwrr     25
2     dwrr     25
3     dwrr     25
4     dwrr      0
5     dwrr      0
6     dwrr      0
7     dwrr      0

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>