RDMA/bnxt_re: Add extended psn structure for 57500 adapters

The new 57500 series of adapter has bigger psn search structure.  The size
of new structure is 16B. Changing the control path memory allocation and
fast path code to accommodate the new psn structure while maintaining the
backward compatibility.

There are few additional changes listed below:
 - For 57500 chip max-sge are limited to 6 for now.
 - For 57500 chip max-receive-sge should be set to 6 for now.
 - Add driver/hardware interface structure for new chip.

Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>