i40iw: Correct values for max_recv_sge, max_send_sge

When creating QPs, ensure init_attr->cap.max_recv_sge
is clipped to MAX_FRAG_COUNT.

Expose MAX_FRAG_COUNT for max_recv_sge and max_send_sge in
i40iw_query_qp().

Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Henry Orosco <henry.orosco@intel.com>
Reviewed-By: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>