net: hns3: add tm flush when setting tm

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7B8SA


CVE: NA

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When the tm module is configured with traffic, traffic
may be abnormal. This patch fixes this problem.
Before the tm module is configured, traffic processing
should be stopped. After the tm module is configured,
traffic processing is enabled.

Fixes: 84844054 ("net: hns3: Add support of TX Scheduler & Shaper to HNS3 driver")
Signed-off-by: Hao Lan <lanhao@huawei.com>