RDMA/bnxt_re: Add support for Variable WQE in Genp7 adapters

RDMA/bnxt_re: Add support for Variable WQE in Genp7 adapters

Variable size WQE means that each send Work Queue Entry to HW can use
different WQE sizes as opposed to the static WQE size on the current
devices. Set variable WQE mode for Gen P7 devices. Depth of the Queue will
be a multiple of slot which is 16 bytes. The number of slots should be a
multiple of 256 as per the HW requirement.

Initialize the Software shadow queue to hold requests equal to the number
of slots. Also, do not expose the variable size WQE capability until the
last patch in the series.

Link: https://patch.msgid.link/r/1724042847-1481-2-git-send-email-selvin.xavier@broadcom.com
Signed-off-by: Hongguang Gao <hongguang.gao@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>