cxgbe(4): Allocate offload Tx queues when a card has resources
provisioned for NIC_ETHOFLD and the kernel has option RATELIMIT.
It is possible to use the chip's offload queues for normal NIC Tx and
not just TOE Tx. The difference is that these queues support out of
order processing of work requests and have a per-"flowid" mechanism for
tracking credits between the driver and hardware. This allows Tx for
any number of flows bound to different rate limits to be submitted to a
single Tx queue and the work requests for slow flows won't cause HOL
blocking for the rest.
Sponsored by: Chelsio Communications