RDMA/nes: Rewrite expression to avoid undefined semantics

Change code like

	x = expr(++x)

that assigns to x twice without a sequence point in between to the
intended (and well-defined)

	x = expr(x + 1)
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/nes/nes_hw.c

@@ -1970,7 +1970,7 @@ void nes_destroy_nic_qp(struct nes_vnic *nesvnic)
 			dev_kfree_skb(
 				nesvnic->nic.tx_skb[nesvnic->nic.sq_tail]);
 
-		nesvnic->nic.sq_tail = (++nesvnic->nic.sq_tail)
+		nesvnic->nic.sq_tail = (nesvnic->nic.sq_tail + 1)
 					& (nesvnic->nic.sq_size - 1);
 	}