net: hns3: refactor dump reg dcb info of debugfs

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

The display style is below:
$ cat dcb
qset_id  roce_qset_mask  nic_qset_mask  qset_shaping_pass  qset_bp_status
0000           0x1            0x1             0x1               0x0
0001           0x1            0x1             0x1               0x0
0002           0x1            0x1             0x1               0x0
0003           0x1            0x1             0x1               0x0
0004           0x1            0x1             0x1               0x0
0005           0x1            0x1             0x1               0x0
0006           0x1            0x1             0x1               0x0
0007           0x1            0x1             0x1               0x0
pri_id  pri_mask  pri_cshaping_pass  pri_pshaping_pass
000       0x1           0x0                0x1
001       0x1           0x0                0x0
002       0x1           0x0                0x0
003       0x1           0x0                0x0
004       0x1           0x0                0x0
005       0x1           0x0                0x0
006       0x1           0x0                0x0
007       0x1           0x0                0x0
pg_id  pg_mask  pg_cshaping_pass  pg_pshaping_pass
000      0x1           0x0               0x1

Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>