net: hns3: Fix initialization when cmd is not supported

When ae_dev doesn't support DCB, rx_priv_wl_config,
common_thrd_config and tm_qs_bp_cfg can't be called, otherwise
cmd return fail, which causes the hclge module initialization
process to fail.
This patch fix it by adding a DCB capability flag to check if
the ae_dev support DCB.

Fixes: 46a3df9f ("net: hns3: Add HNS3 Acceleration Engine & Compatibility Layer Support")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>