net: hns3: debugfs add max tm rate specification print

In order to add a method to check the specification of max tm rate
for debugging, function hns3_dbg_dev_specs() adds this value print.

Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>