net: hns3: fix mixed flag HCLGE_FLAG_MQPRIO_ENABLE and HCLGE_FLAG_DCB_ENABLE

HCLGE_FLAG_MQPRIO_ENABLE is supposed to set when enable
multiple TCs with tc mqprio, and HCLGE_FLAG_DCB_ENABLE is
supposed to set when enable multiple TCs with ets. But
the driver mixed the flags when updating the tm configuration.

Furtherly, PFC should be available when HCLGE_FLAG_MQPRIO_ENABLE
too, so remove the unnecessary limitation.

Fixes: 5a5c9091 ("net: hns3: add support for tc mqprio offload")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>