Initialize various DDP parameters in the main cxgbe(4) driver:

• Setup multiple DDP page sizes. When the driver attempts DDP it will try to combine physically contiguous pages into regions of these sizes.

• Set the indicate size such that the payload carried in the indicate can be copied in the header mbuf (and the 16K rx buffer can be recycled).

• Set DDP threshold to the max payload that the chip will coalesce and deliver to the driver (this is ~16K by default, which is also why the offload rx queue is backed by 16K buffers). If the chip is able to coalesce up to the max it's allowed to, it's a good sign that the peer is transmitting in bulk without any TCP PSH.

MFC after: 2 weeks