IB/rdmavt, IB/hfi1, IB/qib: Add inlines for mtu division

Add rvt_div_round_up_mtu() and rvt_div_mtu() routines to
do the computation based on the pmtu and the log_pmtu.

Change divides in qib, hfi1 to use the new inlines.

Reviewed-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/rc.c

@@ -2377,8 +2377,7 @@ send_last:
 			 * Update the next expected PSN.  We add 1 later
 			 * below, so only add the remainder here.
 			 */
-			if (len > pmtu)
-				qp->r_psn += (len - 1) / pmtu;
+			qp->r_psn += rvt_div_mtu(qp, len - 1);
 		} else {
 			e->rdma_sge.mr = NULL;
 			e->rdma_sge.vaddr = NULL;