RDMA: Constify the argument of the work request conversion functions

When posting a send work request, the work request that is posted is not
modified by any of the RDMA drivers. Make this explicit by constifying
most ib_send_wr pointers in RDMA transport drivers.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/nes/nes_verbs.c

@@ -3040,7 +3040,8 @@ static int nes_process_mad(struct ib_device *ibdev, int mad_flags,
 }
 
 static inline void
-fill_wqe_sg_send(struct nes_hw_qp_wqe *wqe, struct ib_send_wr *ib_wr, u32 uselkey)
+fill_wqe_sg_send(struct nes_hw_qp_wqe *wqe, const struct ib_send_wr *ib_wr,
+		 u32 uselkey)
 {
 	int sge_index;
 	int total_payload_length = 0;