net: hns3: fix ETS bandwidth validation bug

Some device only support 4 TCs, but the driver check the total
bandwidth of 8 TCs, so may cause wrong configurations write to
the hw.

This patch uses hdev->tc_max to instead HNAE3_MAX_TC to fix it.

Fixes: e432abfb ("net: hns3: add common validation in hclge_dcb")
Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>