i40e/i40evf: Use dma_rmb where appropriate

Update i40e and i40evf to use dma_rmb.  This should improve performance by
decreasing the barrier overhead on strong ordered architectures.

Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -1554,7 +1554,7 @@ static int i40e_clean_rx_irq_ps(struct i40e_ring *rx_ring, int budget)
 		 * any other fields out of the rx_desc until we know the
 		 * DD bit is set.
 		 */
-		rmb();
+		dma_rmb();
 		if (i40e_rx_is_programming_status(qword)) {
 			i40e_clean_programming_status(rx_ring, rx_desc);
 			I40E_RX_INCREMENT(rx_ring, i);
@@ -1745,7 +1745,7 @@ static int i40e_clean_rx_irq_1buf(struct i40e_ring *rx_ring, int budget)
 		 * any other fields out of the rx_desc until we know the
 		 * DD bit is set.
 		 */
-		rmb();
+		dma_rmb();
 
 		if (i40e_rx_is_programming_status(qword)) {
 			i40e_clean_programming_status(rx_ring, rx_desc);

drivers/net/ethernet/intel/i40evf/i40e_txrx.c

@@ -1034,7 +1034,7 @@ static int i40e_clean_rx_irq_ps(struct i40e_ring *rx_ring, int budget)
 		 * any other fields out of the rx_desc until we know the
 		 * DD bit is set.
 		 */
-		rmb();
+		dma_rmb();
 		rx_bi = &rx_ring->rx_bi[i];
 		skb = rx_bi->skb;
 		if (likely(!skb)) {
@@ -1213,7 +1213,7 @@ static int i40e_clean_rx_irq_1buf(struct i40e_ring *rx_ring, int budget)
 		 * any other fields out of the rx_desc until we know the
 		 * DD bit is set.
 		 */
-		rmb();
+		dma_rmb();
 
 		rx_bi = &rx_ring->rx_bi[i];
 		skb = rx_bi->skb;