bnxt_en: only set dev->queue_mgmt_ops if supported by FW

The queue API calls bnxt_hwrm_vnic_update() to stop/start the flow of
packets, which can only properly flush the pipeline if FW indicates
support.

Add a macro BNXT_SUPPORTS_QUEUE_API that checks for the required flags
and only set queue_mgmt_ops if true.

Signed-off-by: David Wei <dw@davidwei.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>