net: hns3: reset DWRR of unused tc to zero

Currently, DWRR of tc will be initialized to a fixed value when this tc
is enabled, but it is not been reset to 0 when this tc is disabled. It
cause a problem that the DWRR of unused tc is not 0 after using tc tool
to add and delete multi-tc parameters.

For examples, after enabling 4 TCs and restoring to 1 TC by follow
tc commands:

$ tc qdisc add dev eth0 root mqprio num_tc 4 map 0 1 2 3 0 1 2 3 queues \
  8@0 8@8 8@16 8@24 hw 1 mode channel
$ tc qdisc del dev eth0 root

Now there is just one TC is enabled for eth0, but the tc info querying by
debugfs is shown as follow:

$ cat /mnt/hns3/0000:7d:00.0/tm/tc_sch_info
enabled tc number: 1
weight_offset: 14
TC    MODE  WEIGHT
0     dwrr    100
1     dwrr    100
2     dwrr    100
3     dwrr    100
4     dwrr      0
5     dwrr      0
6     dwrr      0
7     dwrr      0

This patch fixes it by resetting DWRR of tc to 0 when tc is disabled.

Fixes: 84844054

 ("net: hns3: Add support of TX Scheduler & Shaper to HNS3 driver")
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>