RDMA/bnxt_re: Add helper data structures

Adding few helper data structure which are useful to initialize hardware
send wqe in variable wqe mode.

Adding a qp flag in HSI to indicate variable wqe is enabled for this qp.

Link: https://lore.kernel.org/r/1594822619-4098-5-git-send-email-devesh.sharma@broadcom.com


Signed-off-by: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>