RDMA/cxgb3: Fixes for zero STag

RDMA/cxgb3: Fixes for zero STag

Handling the zero STag in receive work request requires some extra
logic in the driver:

 - Only set the QP_PRIV bit for kernel mode QPs.

- Add a zero STag build function for recv wrs. The uP needs a PBL
  allocated and passed down in the recv WR so it can construct a HW
  PBL for the zero STag S/G entries.  Note: we need to place a few
  restrictions on zero STag usage because of this:

  1) all SGEs in a recv WR must either be zero STag or not.  No mixing.

  2) an individual SGE length cannot exceed 128MB for a zero-stag SGE.
     This should be OK since it's not really practical to allocate
     such a large chunk of pinned contiguous DMA mapped memory.

- Add an optimized non-zero-STag recv wr format for kernel users.
  This is needed to optimize both zero and non-zero STag cracking in
  the recv path for kernel users.

 - Remove the iwch_ prefix from the static build functions.

 - Bump required FW version.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>