net/mlx4_en: break out tx_desc write into separate function

In preparation for writing the tx descriptor from multiple functions,
create a helper for both normal and blueflame access.

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c
index 8db8405..768085f 100644
--- a/drivers/infiniband/hw/mlx4/qp.c
+++ b/drivers/infiniband/hw/mlx4/qp.c
@@ -232,7 +232,7 @@
 		}
 	} else {
 		ctrl = buf = get_send_wqe(qp, n & (qp->sq.wqe_cnt - 1));
-		s = (ctrl->fence_size & 0x3f) << 4;
+		s = (ctrl->qpn_vlan.fence_size & 0x3f) << 4;
 		for (i = 64; i < s; i += 64) {
 			wqe = buf + i;
 			*wqe = cpu_to_be32(0xffffffff);
@@ -264,7 +264,7 @@
 		inl->byte_count = cpu_to_be32(1 << 31 | (size - s - sizeof *inl));
 	}
 	ctrl->srcrb_flags = 0;
-	ctrl->fence_size = size / 16;
+	ctrl->qpn_vlan.fence_size = size / 16;
 	/*
 	 * Make sure descriptor is fully written before setting ownership bit
 	 * (because HW can start executing as soon as we do).
@@ -1992,7 +1992,8 @@
 			ctrl = get_send_wqe(qp, i);
 			ctrl->owner_opcode = cpu_to_be32(1 << 31);
 			if (qp->sq_max_wqes_per_wr == 1)
-				ctrl->fence_size = 1 << (qp->sq.wqe_shift - 4);
+				ctrl->qpn_vlan.fence_size =
+						1 << (qp->sq.wqe_shift - 4);
 
 			stamp_send_wqe(qp, i, 1 << qp->sq.wqe_shift);
 		}
@@ -3169,8 +3170,8 @@
 		wmb();
 		*lso_wqe = lso_hdr_sz;
 
-		ctrl->fence_size = (wr->send_flags & IB_SEND_FENCE ?
-				    MLX4_WQE_CTRL_FENCE : 0) | size;
+		ctrl->qpn_vlan.fence_size = (wr->send_flags & IB_SEND_FENCE ?
+					     MLX4_WQE_CTRL_FENCE : 0) | size;
 
 		/*
 		 * Make sure descriptor is fully written before